Knocking Up Sister's Best Friend - Cover

Knocking Up Sister's Best Friend

by Lubrican

Copyright© 2005 by Lubrican

Erotica Sex Story: Brad can't keep his mind off Elizabeth, his sister's best friend and, in a fit of frustration he shows her just what happens when he thinks about her. That leads them down a path that makes her belly swell. But the story isn't over there. What will sister do to the man who ruined her friend?

Caution: This Erotica Sex Story contains strong sexual content, including mt/ft   Teenagers   Consensual   Romantic   Heterosexual   Incest   Brother   Sister   Rough   First   Petting   Pregnancy   .

Brad was bummed. It was Saturday again. He was beginning to hate Saturdays. It was supposed to be a day he could have fun and do what he wanted, but ... Elizabeth would be here most of the day.

He knew she would.

She always did that on Saturdays.

She also came over to see his sister Renee every day after school too. They were best friends. It wasn't so bad during the week, because he could stay in his room and do homework or at least pretend he was doing homework. Then he could maybe keep his mind off her.

Elizabeth and he were both ninth graders, so he had been plagued with her for over two years. Ever since he had noticed ... well ... HER. He'd known her forever. She'd gravitated to his younger sister when they'd moved to this one horse town and stuck like glue ever since. Technically they were a year apart, but in reality it was only three months. Elizabeth was born in October and Renee the following January.

He thought of her now. Her breasts. Wow, what boobs she had. They stuck out now so much that he almost couldn't look at any other parts of her. Not that those were bad either. She had what they call an Elfin face, with short straight hair down to the bottom of her jawbone. When she shook her head it flew in all directions and then just lay right back down where it belonged. Her eyes were dark green and she had plump ... kissable lips. She wasn't skinny, but she wasn't really fat either. She had flesh everywhere, but it was shaped just right. Her hips went out from her sides somehow so that if you were facing her she looked like someone was blowing up a balloon there, under her pants, but it made her marvelous breasts look just right somehow. She wore halter tops all the time in the summer, with no bra. In the winter she wore these thin sweaters that curved to the shape of her boobs like skin. She was tall for a girl, probably 5' 10" and her legs were really long looking. She was almost as tall as he was now and he was afraid she was going to catch up some day.

Every time he saw her his dick got hard. Just like it was right now and all he was doing was thinking about her. It had gotten to the point that he had to jack off twice a day! All he had to do was imagine her naked, holding her arms out to him and he'd spurt three feet. He'd actually seen her naked - lots of times - but that was years ago when they skinny dipped in the creek. She didn't have any real breasts then, and he couldn't put the mountains she how had on that memory for some reason. It made her look like she'd fall over or something.

And she'd be around all day today.

And he'd be tormented and have to find some time and privacy to beat off while she was there. That or walk around bent over all day. She didn't actually tease him or anything. She was actually nice to him. They were friends, after all, and had been for a long long time. She treated him lots better than Renee did.

He'd swear his sister hated the air he breathed. She was always calling him "toad face" or "shit-for-brains" (but only when there were no adults around for that one), or "Wimpy". He didn't get it. He certainly didn't look like a toad. He got straight "A"s in school. He won the swim meet nearly every year and was in fabulous shape. What was her deal?

He didn't hate HER. He thought she was beautiful. Well, more like cute. She was blond and wore her long hair in a pony tail most of the time. Sometimes dog ears. Her boobs weren't as big as Elizabeth's. He'd seen her naked at one time or another all his life. She had interesting nipples. The areola of each breast was thick and puffy and stood out from the breast flesh like a little pillow or something. Then, on top of that was a big fat nipple. The nipple and areola were almost exactly the same color, and if you were facing her she just had large brown circles in the middle of her breasts. But if she stood sideways you could see that her nipple actually stood out half an inch or so. She hated her breasts because if she wore anything thin without a bra that whole silver dollar sized pillow-with-a pencil-eraser-on-it stuck out and made her look what she thought was deformed or something.

He remembered seeing her a couple of weeks ago, coming out of the shower. She was naked, of course, and was drying her hair with a towel as she walked back to her room. Her arms were above her head and her breasts were stretched upwards a little. He was surprised to find himself thinking that those brown circles looked just the perfect size to fit in a guy's mouth.

He was horrified to find that he had to beat off before he could think about anything else.

Part of the problem was that Renee had a paper route. She made pretty good money at it, but she had to do her route six days a week. She used to ride her bike and it only took an hour, but nowadays she said she was "too big" to ride a bike and walked it. That took two hours.

It was those two hours that Elizabeth would be sitting in his room, or on a chair near him, wherever he was, talking.

Talking, talking, talking.

And when she talked she breathed.

And when she breathed, those fabulous tits moved.

And when those tits moved he got a major boner.

On weekdays he could pay attention to his homework. And try to ignore her while she did her own, or read a book or applied makeup or whatever.

On Saturdays he had no excuse not to pay attention to her. Play a board game with her. Do a picture puzzle with her. Do something with her for two hours.

And then whack off like crazy when Renee got back and they went to her room.

He heard the front door slam, and Elizabeth's voice call out.

Oh no! He wasn't ready. All he had on was the gym shorts he'd slept in. They were loose and baggy and that was bad! Usually he found his tightest jeans on Saturday and folded his six incher down into one leg. Then when it got firm the jeans would confine it.

It hurt, but it didn't embarrass him.

Then he usually put on a football jersey that hung down to his thighs. Then he was safe. But now, the minute he saw her, his wang would stand at attention and poke straight out in his shorts!

He put down the egg sandwich he'd been having for breakfast and fled for his room.

He slammed right into Elizabeth as she came around the corner. She was taking her coat off and his chest bounced right into hers.

"Ow!" she yelped. "Watch where you're going Brad."

It was happening already. He could feel the blood literally rushing into his tube.

"Sorry" he mumbled and tore up the stairs, passing his sister who was on the way down.

"What's wrong with him?" he heard Elizabeth say as she saw Renee.

"He's got shit for brains" Renee said loudly. That meant his parents were already gone on their shopping trip for a new couch. That meant they'd be gone most of the day too. They were going to Kansas City, which was three hours away. Now he couldn't use them to deflect Renee's insults.

He sat in his room, wondering what to do. Icewind Dale! That was it. It took real concentration and a game could last for hours. He flipped on the computer and sat down. Dad had the wood stove going again at full blast. It was hot in the house. He didn't put anything else on.

It was some time later that he heard Elizabeth come into his room. He was in real trouble in an old castle and was going to have to play this perfectly or he'd lose his wizard and his thief. He'd made his thief a woman - an Elven woman - and had named her Liz, because all women reminded him of Elizabeth. Even the character on the screen had the capacity to make his dick stiffen. He wondered if there was something wrong with him.

He tried to ignore Elizabeth. She knew about the game and usually didn't bother him, especially when there were red circles all over the screen. But today she intruded.

"Brad? Can I talk to you about something?" "Brad?... Brad!!"

The undead surrounding him attacked and his green circles started dimming. He was toast. There was his beautiful Liz, lying dead on the ground.

"What?!" he yelled, not without some passion in his voice.

"What in the world is wrong with you today?" she said, the hurt obvious in her voice. He hadn't looked at her yet.

"Nothing." he growled. He felt her hand on his shoulder and jerked away from it.

"Bradley Ray Stokes! There most certainly is something wrong with you. What is it? Please? Tell me. Let me help. You're my friend."

Suddenly he realized he hadn't put anything on. He was helpless. It was going to happen. Just because of her voice ... it was already starting. His frustration boiled over. He swiveled to face her. In some dim recess of his mind he noticed she was wearing the lavender sweater - his favorite. Another not so dim part of his mind told him to just shut up and flee to the bathroom.

But the frustration took over.

He looked at her face, her eyes, her lips and his gaze slid irresistibly down to her breasts.

Yup, just like clockwork, maximum boner.

"This is what is wrong Elizabeth!" he shouted and stood up, facing her. She looked blank for a minute, staring at his face, not understanding, and then, naturally, she looked at the rest of his body. She saw it. She couldn't miss it, of course, but she actually jumped as she saw the tent in the front of his shorts. "Yes, this is what's wrong with me. Today, yesterday - Every day you're here! I can't control it. Sometimes it hurts, and I'm tired of it!"

There was a tear in his eye. Oh no! Not that, please not that. He got control of himself and his eyes did not overflow, but Liz saw them full of moisture. She stood there, her mouth open in a little "o".

Then she jumped again. "Every day I'm here?" she said, her voice going high.

The anger had flown out of him. He'd made a fool of himself, he just knew it. To his amazement his dick started to go limp. Not all the way, but it sagged a good three inches. Now it was just a large bulge in his shorts, and not a real tent.

"Yes." was all he said.

"Wow" she said and then, she laughed.

He turned on her, a storm on his face "Don't you laugh!"

She put her hands up, warding him off and her face got serious "No! Brad! That's not why I was laughing. I was laughing because what I came in here to try to get you to do was kiss me, but I was afraid you would laugh at me. I thought it was funny that I was all nervous about it because I was afraid you wouldn't want to but ... I guess you do." she finished in an amazed voice.

Now it was Brad's jaw that dropped. "Kiss you?"

Now she was nervous. No boy had ever gotten a boner over her. Not that she knew about anyway. It made her pussy feel tingly. "Well ... um ... uh..." she stammered. "Roger Collins asked me to go out on a date with him, and I never went out with anybody before, and I know he'll want to kiss me and I didn't want to do it all wrong and mess it up, so I thought maybe you'd ... well ... practice with me sort of." She took a big breath after such a long sentence. Man those tits were amazing.

In a daze, Brad couldn't believe he was nodding his head. Well, he could believe it, but he couldn't believe it was happening.

Suddenly he was suspicious. Renee was probably hiding somewhere, with a camera or something and was going to jump out and scream or something if he kissed Elizabeth. "Where's Renee?" he asked.

"Oh" said Elizabeth "She's on her paper route. But you can't tell her. Please. You have to promise me you won't tell her we did this. Please? Brad? Please?"

"Oh I understand completely" he said. "She'd never let us live it down. You really want me to kiss you?" He still couldn't believe it.

"Yes!" she squealed, then blushed. "I mean if it's okay with you."

He looked down at his still admirable bulge and then grinned. "Well Duh."

She giggled nervously.

They approached each other tentatively. She had to tilt her head up just a fraction, and, to get close enough to touch his lips with hers, she had to push her breasts against his chest.

The kiss was magical.

First their lips brushed. Hers were dry, and without thinking about it she licked them, licking his in the process. Then their moist lips pressed together.

It was amazing.

She wanted to be sucked into his body through those warm soft lips of his. She tasted his lips again with her tongue and to her amazement felt his tongue tip dart against hers. She moaned as she felt pain in her nipples. It was a sweet pain that was somehow connected directly to her lips.

He on the other hand was not at all surprised when his cock leapt back to full rigidity. It was even better than he had dreamed. And she had licked his lips! He felt the soothing rush of liquid in his penis and realized he had leaked some cum - probably a lot, since it felt so good. Neither of them breathed during the whole wonderful thing.

It was that fact that ended the kiss. They had to breathe and they broke apart gasping for air.

"Wow" Liz said in an awed voice. "I didn't know it would be like that. "I'm not sure I actually want to feel like that with Roger. Wow. Is it hot in here?" She was babbling as she took her sweater off. Under it she had on a man's tank top.

Brad stared at her breasts.

She noticed and giggled.

He blushed and looked away, but she said "It's oaky. I know boys look at them. I think they're ugly, but boys seem to like them. Even my dad looks at them sometimes. Hey! What happened?"

She was pointing at his shorts. The tent was back, the shorts stretched tight, and there was a dark circle of moisture about two inches around the tip of the tent. Now Brad flushed beet red.

"I ... uh ... I sort of ... leaked while we were kissing."

"Leaked? You mean you peed your pants?" she looked horrified.

"No! No! It's not pee. It's..."

Her eyes got round as she finally understood "Oh!" and then she giggled again.

He wasn't mad this time. "It really isn't funny, Liz."

"Oh I know. It's just that nobody ever ... leaked ... because of me before."

"Oh yes they have," he said, not realizing he'd said it out loud. When he saw she had heard him and was about to ask him about it he went on. "I have. Daily. All the time. Every time you come over I have to ... well, it leaks, okay?"

"No, I don't understand. What do you mean?" She looked completely serious.

"You know" he made the air jerking motions that every teenager understood meant that a boy was jacking off.

"Oh!!" she gasped. Suddenly she felt that sweet pain in her nipples again. He jerked off because of her! It still felt hot and she waved the tank top around to get some air to her torso.

"I'm sorry" he said miserably.

"No! Brad! It's okay. Really it is. It makes me feel ... pretty or something. It makes me feel things..."

She couldn't finish, but looked down at her thrusting mounds.

"Brad, would you kiss me again?"

Overjoyed that she didn't hate him he embraced her. This time her body came against his completely as their lips locked. This put the tip of his hard cock right above where her pubic hair started and it poked into her. She felt weak as she realized what it was and kissed him even harder. Her nipples were at it again. She unconsciously took her hands off his shoulders and squeezed a nipple with each of them, and the ache lessened.

But really it just transferred.

Now she felt the tingle between her legs.

The kiss went on and on as they figured out how to get snatches of air while their tongues dueled through open lips. When they parted she said "I have to sit down." The nearest thing to sit on that both of them could sit on was the bed.

They kissed again. And again, and soon they were lying side by side, their hands sliding over each other's backs, shoulders, heads. Brad was in pain now, and finally he rolled back, groaning.

"What's wrong?" Liz asked.

"My bal ... I'm in pain," he groaned. "I need to go to the bathroom or something."

"Or something?" she asked.

"Yeah. I need to ... you know."

She gasped and her gaze went straight to his shorts. The stain was larger now. "You're going to ... jerk off?"

"Yeah" he groaned. "It sort of builds up and hurts until I release the pressure." He started to get up.

"No! Wait!" she yelled. He stopped and turned, puzzled. "Can you ... do it ... here? Can I ... see you do it?"

Brad was actually glad at that very moment that his balls hurt so much or he'd have shot his wad in an instant. He also wasn't going to look a gift horse in the mouth, or give her time to think about it and change her mind.

Without a word he skinned his shorts down and stood, naked, before her. She gasped again as she saw what had made the tent. It was red and long and hard and pointed. It looked angry to her. His hand closed around it and he stroked. There was a bunch of loose skin at the tip that slid back when he pulled on it and uncovered a shiny knob at the end. It was the knob that was pointed, she saw, and the skin just took its shape. She saw a little hole at the tip and a pearly drop of liquid seeped out. She knew at once it wasn't piss. It was thick and whitish looking. It was sperm, she realized. She felt a lance of tingling pain in her pussy and had to squeeze her nipples again. He was staring at her hands as her finger tips squeezed and he gasped.

Suddenly she wanted to touch it.

"Can I ... try it? Do it for you?" she whispered.

A big glob of the white stuff bulged out of the little hole when she said that. He stumbled over to the bed and flopped on it beside her. His hand came away and hers tentatively grasped that angry hard staff.

"Oooooo" she cooed as she realized it only looked rock hard. Actually it was spongy and felt really good in her hand. The tip leaked more sperm and she realized why the stain on his shorts was so big.

And she was making it happen! Her pussy itched now.

Brad felt the climax approaching. Her hand on his prick felt so wonderful he almost forgot to warn her. But he knew what would happen when he came.

"Liz ... it shoots out ... really hard. It'll get all over your clothes."

She heard him, but didn't want to stop what she was doing. Suddenly she was tearing at her tank top, pulling it over her head. Then she shucked out of her jeans and tossed both garments toward the door.

Now it wouldn't get all over her clothes.

Brad stared in awe at the girl pulling his pud, now dressed only in bra and panties. The bra showed him more of her breast than he'd ever seen before.

He had to ask.

"Liz, could you please take your bra off for a minute?"

She was so enraptured with watching the loose skin hide and then uncover his shiny knob that she just reached around, popped the clasp and shrugged the bra off. It hung up on the wrist she was holding his penis with, and draped across his groin.

There, displayed in all their glory, were the breasts he had dreamed of seeing. They were very different from his sisters. They were round and hung away from her body as she leaned over him. Her areolas were only the size of a quarter and light pink, with a darker plainly visible nipple on top. Her nipples looked just about like Renee's, though. They looked hard and stiff. Seeing them was all it took to break the dam in his balls.

"Ohhhhh Lizzzzzz" he groaned.

She knew something was going to happen and leaned closer to look.

Just then a long rope of thick white fluid burst from the tip of his penis and splatted right on her right breast. It was hot! She felt it run and hang from a nipple and immediately brought up her free hand to squeeze that nipple. The sperm on it lubricated it and she moaned as she felt the thrills shoot from the nipple to her pussy. Then his dick was spurting more of the stuff. She managed not to get any on her face, but both breasts, her stomach, his stomach and a lot of the bed spread were spotted with it. There was so much. He was moaning and groaning and his hips were raising up off the bed. He sounded like he was in pain, but she knew somehow that he wasn't. She had made him feel this way! She felt so proud of herself. And she wanted to kiss him again. She lay down beside him and pressed her naked chest to his as she sought his lips. That felt good too, even with the slippery cooling sperm all over her. Her pussy itched fiercely and she wanted to rub it.

They snuggled and kissed for ten minutes before Brad lifted his head and looked at the clock. "Hey, we've got to get cleaned up. Renee will be back soon."

"I don't think so" said Liz. "It snowed last night and there's eight inches on the ground. It's going to take her hours to get around her route.

Brad jumped up and peered out the window. A thick layer of white covered everything. Normally he'd have been overjoyed, thinking of going out in it. But now he was overjoyed because it would give him just a little more time with Liz.

"Come with me" he said, grabbing her hand.

They ran to the bathroom and he turned the shower handle to hot. He looked at her, and with only a little blush she bent to remove her panties. Then she took off her socks. They got into the shower together, and it only seemed normal to wash each other. She washed him first, running her hands over his chest, feeling his pecks and then kissing him as she rubbed her body up against his. Then he ran his soapy hands over her, lingering at her breasts, teasing the nipples. Liz felt the fire begin to build in them and run to her pussy. Before he could touch her between her legs she was against him, kissing him deeply.

His dick rose again, between her legs, and pressed in between her labia. Now something was rubbing her pussy, and it felt fabulous. She didn't want it to stop. But he was turning the water off. They got out and he gave her a towel. They hurriedly dried off and then she picked up her panties and socks and they left to go back to his room.

"Brad?"

"Yeah Liz?"

"What does it feel like ... when you ... when you cum?"

"Gosh. I don't know how to describe it. I suppose it feels a lot like it feels when you cum. Why don't you tell me about that and we can compare."

She was silent for a few seconds. "I ... I'm not sure I ever have cum," she said softly.

"Don't you ... you know ... rub yourself?" He assumed all girls did. He knew Renee did because he'd spied on her one time and saw her doing it on top of her covers.

"Oh no. I mean, my mom told me when I was little that it was very bad to do that, and that I'd hurt myself and maybe even go blind if I ever did it."

Brad was stunned. He tried to think about what his own life would have been like if he couldn't jack off.

He'd have just died. That's all. He'd have croaked by the time he was twelve.

But he'd heard the same stories. Not from his parents - they hadn't said anything at all to him - but from other kids. He knew it was bullshit.

"I don't think that's true at all." he said. "I mean I've been beating my meat for years now, and I haven't grown any hair on my palm, or gone blind or crippled or any of that stuff. You should try it. It feels really good."

"I know it does." she blushed a little. "When we were in the shower and your ... cock ... was touching me there, it rubbed and it felt really really good." There was more silence. "Could we do that some more?"

Brad's head was spinning. He'd never actually fucked a girl. He'd seen it on lots of videos at his friend's houses, but he'd always been too shy to try anything with a girl. Not that what she was talking about was actually fucking. But it was close, and he remembered the feeling too.

"Yeah" he said tightly. "I think I'd like that too."

"I can see that" she said, amusement tingeing her voice. He hadn't even felt his cock go hard. But it was at full measure again, standing out proudly. They embraced and began a slow sort of dance, during which they kissed hotly and his cock rubbed along the furrow of her pussy. He felt her get slick, and his cock slid through much easier. She was breathing harder now. But there was only so much pressure that could be applied in that situation.

"I have an idea" she said, panting. She walked him backward until the back of his knees hit the edge of the bed. Then she shoved him in the chest and he flew backward onto the bed. She leapt after him and landed straddling his hips. She sat on his knees and bent over to jack his cock a few times.

"I love the way it feels" she said as she watched his glans play hide and seek inside his foreskin. Then she lay it down on his stomach and scooted forward until her pussy lips straddled the firm underside of his cock. She let her weight down and pressed his organ into his abdomen.

"Mmmmmmm" she said as she slid her pussy forward along his tube. "That's better."

She started making long slow movements, dragging her pussy mouth along the length of his dick. He'd never felt anything quite like it. Knowing what was doing it started his dick leaking again and soon there was a puddle of precum on his stomach. Liz was obviously having a good time too as she made her movements more rapid. She leaned over to kiss him just as she scraped her pussy forward and, for the first time, her little unused clitty made contact with his knobby prick. Her head whirled as stabs of pleasure streaked through her young body.

"Oh!" she gasped. "Ohhhh Ohhhh Ohhhhhhhhh". She leaned back up, but not far enough to break clitoral contact, and suddenly her breasts were hanging right in Brad's face. He couldn't resist. His head came up and he gobbled one nipple, sucking it into his mouth. It was hard and firm, and he was able to get a grip on it with his teeth so it couldn't slip right back out of his mouth.

That was the fateful moment. Already in constant and almost violent pleasure from rubbing her clit over his wonderful cock, the added stimulus of having her nipple suckled for the first time caused her to fall headlong into her first real climax. She felt it start in her pelvis as an almost electric tingling, which rapidly spread throughout her stomach, up to her breasts and then somehow into her brain.

Her lunges became frantic. She bent forward more, to keep his mouth in contact with her aching nipple, and that lined her pussy up with the length of his cock. As she lunged back toward his balls, the head of his cock slid neatly into her open pussy hole and in one violent lunge she impaled herself halfway to his balls. The flash of pain associated with her torn hymen came right in the middle of her orgasm, which she now realized in some small part of her brain was in fact an orgasm. She felt the tearing as pain, but assumed it was part of what was happening to her - part of the orgasm. And, in truth, the pain lasted only a few seconds. Then the fullness of her vagina registered, and her nerves identified the foreign body as something hot and firm and she realized what had happened.

She gasped "Oh! Oh Brad! It's in meeeeeee! Your cock went in meeeee. Oh, it's inside meeee. Oh shit!" Her gyrations got even wilder as she instinctively wormed her pussy further onto his stiff rod. The pleasure of being filled as it went deeper and deeper into her was indescribable.

Brad too knew what had happened. He'd been happily sucking on her juicy nipple when sudden heat surrounded his cock. Then his cock was squeezed like nothing he'd ever felt before. Then the tip of his cock reached her cervix and happened to be lined up to nudge right into that opening. It wasn't quite long enough to penetrate clear into her womb, but those cervical lips were spasming with her orgasm and they nibbled at the head of his cock. Truth to tell he'd been close to squirting anyway, but the nibbling on the head of his cock made him lunge upward and that popped the tip of his cock into her womb. His penis fired immediately.

He felt the stream of cum as it left his balls and raced through his penis. The sweet release flooded his consciousness as it rocketed out of the end of his prick ... and straight into her womb. That jet was followed by six or seven more and they were the type that would have indeed shot two or three feet in the air. Brad went crazy, grunting and huffing and puffing and thrusting.

Liz felt the splats of hot juice in her womb and found out that an orgasm can be even better.

Little did either of them know there was an egg floating around, floating in a sea of sperm.

They all attacked.

Only one got through.

Brad and Liz both started awake. They had lain there, catching their breath and had dozed off, so comfortable they were cuddled together. Brad checked the clock and panicked. If Renee wasn't home already she would be soon. Frantically they both leapt out of bed, grabbed their clothes and dressed. Brad put on a pair of jeans and T shirt. He had just finished getting his sheets started in the washer when he heard Renee come in.

 
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