Science Affair
Copyright© 2025 by Anonymous
Chapter 3
Young Adult Sex Story: Chapter 3 - A high school boy starts a science project with his best friend that ends up changing their lives.
Caution: This Young Adult Sex Story contains strong sexual content, including mt/ft mt/Fa Consensual Incest Group Sex Orgy Anal Sex Oral Sex Safe Sex
I awoke slowly to something warm, wiggling, and heavy on my chest. I slowly opened my eyes to see Kathy’s bright blues looking into mine from a couple of inches above. She was lying on my chest and kissing me on the nose with little pecks like a bird.
“Time to get up, stud. It’s almost noon, and Mom will be wondering why we are both so late getting up.” I hugged her, smiled, kissed her hard, and started to get a morning woody that she felt rise to touch her ass.
“No time for that,” she giggled and got off of me. She went into the bathroom and started the shower.
“We have to take separate showers, or Mom might figure it out,” she said from the bathroom. I groggily got out of bed and sat on the edge looking at my feet for a long time. When my mind started functioning, Kathy was in the shower. I looked at my cock and was surprised at the mess. I was covered with dried cum and pussy juice. My pubic hair was a solid mass. It all must have leaked out while Kathy slept on top of me. At least her sheets weren’t a crusty mess! I staggered into the bathroom, pissed, and brushed my teeth. Kathy stuck her head out and told me to muss my bed up a bit in case Mom wanted in. I mumbled an affirmative and proceeded into my room to perform the deed. I sat on my bed to wait for her to finish. She stepped out and dried off by giving me flirty little peeks at her tits, pussy, and ass. It was sexy, and I started getting hard again. She wrapped the towel around her tits and brushed her teeth.
“It’s all yours,” she said cheerily as she went into her room. She was still wrapped in the towel and drying her hair when I stepped in for my shower.
I stepped out of the shower, and her door was closed. I shaved and dressed and went downstairs. Mom was reading the paper at the dining table, and Kathy was eating toast. Mom asked if I wanted her to fix something. I told her I just wanted cereal. As I stared at my Cheerios, they talked as if nothing was out of the ordinary. Man! Kathy was an actress! As I ate, I was dwelling on the events of the past few days. It was an awakening of sorts. My life had changed dramatically. No longer were school, computers, fantasizing about girls with Chuck, and beating off to images of Miss Monroe the all-encompassing checkpoints in my life. I felt my life was suddenly fuller, and I saw events more clearly. Kathy was the main focus of my thoughts, and around her, the aspects of my life were dimmed. How could I function if I was in love with my sister? It had to remain a secret, and we had to function as if it hadn’t happened. Looking at Kathy talk with Mom made me realize she could handle it. Could I? I thought about the events to occur today and tomorrow, and I was eager for them to start.
I asked Mom if Chuck could come over, and we could do her measurements? She laughed, and I realized the double entendre, causing me to blush.
“I can tell them to you if you want to save time.” She continued laughing.
Kathy added to my embarrassment when she chortled, “They would rather do it themselves!”
Mom was laughing as she looked at Kathy and added with a squeal, “What fun!” I looked from Mom to Kathy, and they were looking at each other, nodding and laughing so hard there were tears in their eyes. It was infectious, and I got caught up in it. When we calmed down, I called Chuck and told him to come over.
Kathy left to call one of her friends, and I went out to the garage to set up. I returned to the kitchen as Kathy was telling Mom she was headed to Gina’s. I went to my room and collected the forms when the doorbell rang. When I got downstairs, Chuck was talking to Mom, and his hands were fidgeting in his pockets. Jeez! He was hot for Mom too! Her eyes were sparkling as they talked. It was the same look Kathy had when she was teasing. Was Mom turned on too? She had her arms folded under her breasts, and she seemed to be squeezing them a little. The V-neck shirt she had on was displaying a bit more of her cleavage than before, and I thought her nipples looked bigger than before.
I headed for the garage, and they followed. We sat Mom in the chair, and Chuck sat in front of her to take the face measurements. I sat to the side with the form to write down the measurements. Chuck placed the guide to the frame and positioned the pencil tip to the bridge of her nose. He read off the X and Y readings, and I took down the Z. He moved to the tip of her nose, and she started giggling and wiggling. Chuck told me to hold the guide, and he cupped her chin as he had Kathy and moved the pencil to her nose again. Mom was looking him in the eyes, and hers were sparkling. I looked down, and her nipples were rock hard and poking out farther than Kathy’s had! Jeez! What was there about this that turned women on? Mike told her to hold still, and he was giggling too. He was looking in her eyes and leaning closer. She wrinkled up her nose and stuck her tongue out.
“Hold still, or I’ll spank you!” he laughed.
“Oh, yeah?” Mom chortled.
“Yeah!” He was so close to her now that his chin was against the guide, and his nose was almost touching hers.
“Go ahead and try it!” She shouldn’t have challenged him.
That was it! Chuck pushed the guide out of the way and, still cupping her chin, she reached his other arm around her waist and pulled her toward his lap. Shrieking and laughing, Mom put up a fight, and they wrestled as he grasped her around the waist with both arms and pulled her to his chest. She was laughing and putting up a mock fight as he stood and pushed his chair back with his knees. Mom was at least eight inches shorter than Chuck, and she didn’t weigh much more than 120 pounds. He was handling her easily. As he sat down again, he turned her and laid her stomach across his knees. She was kicking, wiggling, laughing, and screeching out “Oh no! No! Oh no!”
He had his right hand in the middle of her back, holding her down, and as he raised his left hand, he warned her, “Here’s number one!”
Mom, laughing and kicking her legs, brought her left hand back to cover her butt. Chuck grasped her wrist and pushed it out of the way. Mom was shrieking and yelling “Oh no!” and kicked her legs more. I was seeing flashes of her thighs as her dress flipped up from time to time. Chuck grasped her wrist with the hand on her back and pushed his arm down across her back so that he was bent over her at her waist, trapping her upper body under his armpit. She couldn’t move much now. They were both panting and whooping in laughter now.
“Here’s number one!” He shouted and brought his hand down smartly on her ass.
Mom shrieked and laughed! “Nah nah na nah nah! Didn’t hurt!”
“Oh yeah?” Chuck grabbed the hem of her skirt and pulled it up over her back and tucked it under the arm holding her down. Now she was really shrieking, kicking, and laughing. She was wearing baby blue bikini panties, and her ass looked beautiful. Chuck laid his hand on her left butt cheek and said, “Here’s number two!” He lifted his hand and gave her a smart smack. She laughed louder and repeated laughing that it still didn’t hurt. This was getting hot! I had sprung a big woody. Chuck had to have one too, and Mom had to feel it, the way she was lying. Chuck yelled out, “Well then, here’s number three!” He smacked her harder, and it sounded like it must have hurt. He was spanking her square across her butt, and I saw his fingers imprinted on her ass cheek.
Mom shrieked again and laughed! “Nah nah na han nah! Didn’t hurt me!”
“Oh yeah?” Chuck shouted.
“Try this!” He grasped the waistband of her panties and pulled them halfway down her thighs. Now I could see her pussy between her thighs. It was fat and glistening a little.
“Oh no! Don’t spank my bare butt!” Mom was shrieking and laughing so loudly the neighbors could have heard it.
Huck rubbed her ass lightly with his hand and yelled out, “Here’s number 4!” He smacked her bare ass sharply, and the imprint of his hand was pale white for a second, then it turned pink. Mom shrieked, kicked, and laughing, screamed that it still didn’t hurt. Chuck then started a slow cadence of rubbing her ass, giving her a sharp smack, and calling out the number. Mom was gasping after the eighth one and saying in between breaths that it still didn’t hurt. Her ass cheeks were bright pink now, and there was a lot of moisture on her pussy. Chuck’s hand during the rub moved lower, and his fingers ran over the lips of her pussy. Mom moaned and gave a voluptuous wiggle and said again that it still didn’t hurt. Chuck gave her a softer smack and started rubbing her ass longer. Once again, his fingers trailed over her pussy as she moaned and wiggled again. Once again, he smacked her, and this time when he started rubbing her, she spread her legs further apart. Now the lips of her pussy were parted a little, and I could see the bright pink inner lips. This time his fingers slipped in between the lips, and her odor filled my head.
I had had it! I had to either participate or leave. I couldn’t bring myself to touch my own Mom, so I stood and said, “You guys have fun. I have to leave.” Chuck looked up at me with a glazed look in his eyes and nodded.
“Go slow and don’t hurt her.” His eyes focused, and he nodded again. As I got to the door, Mom gasped that it still didn’t hurt. I went into the kitchen, but I didn’t close the door completely. I heard him yell, “Here’s number 9!” The smack was softer than before, and there was a pause, and I heard Mom give a long groan. She gave a loud hiss and then said in a breathless voice, “Still doesn’t hurt!” I had to see, so I peered around the door in time to see Chuck say in a strangled voice, “Here’s number ten!” He was sitting upright now, and the hand that had been on her back was on her opposite butt cheek. He brought his left down in a soft smack on the right cheek and started rubbing her ass with both hands. His left worked its way well under now-widespread legs, and he must have been stroking up to her clitoris.
“Oh, Chuck! Yes!” She gasped and moved her ass in a little fucking motion as he continued to stroke her pussy. This continued for a long minute, and she gasped out that it still didn’t hurt.
“Here’s number 10!” He gasped and smacked her a little harder. His hand went immediately between her thighs, and the moaning and fuck movements increased. He moved his right hand under her body to grope her tits as he finger-fucked her with the other hand. They were both gasping, and her hips were moving faster.
“Yes, honey! Right there!” She cried as her movements increased and she seemed to shake. She quivered as he worked for about a minute, then she sagged a little over his lap. He continued to stroke her pussy. His other hand, out of my sight, must have continued to squeeze her breast. After another minute or two, she lifted her head a little.
“Still doesn’t hurt!” She called out.
“Here’s number 10!” He was so out of it that he had lost count. He smacked her again, and his hand returned to her pussy.
“Chuck, honey, let me up!” She gasped, and he helped her stand. She faced him, bent at the waist, and kissed him for a long time, her hands cupping his face. He ran a hand up under her dress as the kiss continued, and she swayed her ass as he stroked her pussy. Moaning while they kissed, she raised up and said, “Let me.” She reached to the side of her skirt and fiddled with the button and zipper at the side. His hand stayed up under it. They were looking in each other’s eyes as the skirt started dropping over her hips. Chuck lowered his hand, and the skirt puddled on the floor. Her panties were still at mid-thigh. She bent and pushed them down to the floor and stepped out of them as she kicked her shoes off. Her ass was as trim as Kathy’s was, maybe even smaller. Chuck’s hand came up to her pussy again as she lifted her shirt over her head, and she dropped it to the floor. Her bra was the same pale blue as her panties and was one of the soft push-up types. Her tits appeared to be a little larger than Kathy’s and fuller. She reached behind her back and undid the clasp. She gasped out, “Where’s Mike?” I ducked back and waited as Chuck told her I left. I looked back in when I heard Chuck groan. She had dropped the bra and was leaning into him, pressing his face between her breasts. I could see one full breast with a long brown nipple and a pink aureole the size of a silver dollar. They were a little fuller than Kathy’s and had a wonderful shape. They didn’t droop at all. Mom had a real bod!
My cock was hurting by now, and my balls ached. Jeez! Getting blue balls over your mother was not something I ever expected! Chuck had to be going nuts! She bent over him and fumbled with his jeans. The next minute, she pulled them off. His cock was tenting his skivvies, and she pulled them off too. His cock stood up along his belly. Mom straddled his legs, grasped his cock, and sat down on it.
“Oh, shit!” Chuck yelled and wrapped his arms around her as she pulled her tits into his face. Her arms were around his head, and they didn’t move for several minutes. Mom began to rock her hips slowly as Chuck’s face emerged. His hand cupped her breast, and his lips went to the nipple. He switched breasts after a few minutes as Mom kept up the same rocking motion. Chuck threw back his head and yelled as his ass lifted off the chair. He was cumming hard. Mom stayed astride him as he settled down in the chair. She was cooing and whispering to him, and he held her tightly around the waist. They stayed like that for several minutes, and Chuck was whispering to her. She continued to sit astride him, and I never saw his cock pull out. I had to take a breather, so I stepped back from the door and leaned against the wall. My cock was hurting badly, so I pulled it out and squeezed it. It was hotter than I can ever remember. I peeked around the door again with my cock in my hand. Mom was rocking her pelvis forward and back against Chuck now, and his hands were clasping her ass. She was whispering to him as the strokes got longer. Chuck was moving his cock up into her as she slid forward on him. They kept the motion up for several minutes. Sweat was pouring off them, and Mom started talking louder.
“Oh God, Chuck! It’s so good! I love it! That’s it! That’s it!” She was raising her ass higher off him as she slid forward, and I could see his cock slamming into her cunt. Her pussy and his cock were dripping in mixed cum and pussy juice. I could hear the squishing and slurping quite clearly. The chair seat was wet under Chuck’s ass as he raised to slam into her. Her arms were around his neck, helping her lift off him.
“Oh shit, Mrs. Lange!” He muttered over and over. He was getting close again, and Mom’s movements were becoming uncoordinated. She was throwing her head from side to side, and the pace was furious now. Mom was growling, and Chuck was sobbing. Jesus! They were fucking like maniacs! Mom gave a big sob, and I saw her hips surge hard against his cock. It looked like she was trying to rip it off with her pussy. Chuck was saying, “Yes! Yes! Yes!” over and over. Mom made about four more big thrusts and then lay against him, quivering and taking deep, gasping breaths. My squeezing of my cock did it, and I came, shooting spurts of cum against the door. I backed away and leaned against the wall until my breath came back and my legs quit shaking. I zipped up and looked around the door again. Mom was still straddling him, and they were talking softly. Chuck’s hands were roaming over her ass and back as they talked. Once in a while, he would squeeze the breast nearest me and resume stroking her. They interspersed the talking with little kisses. At last, she released him and started to stand. Her legs were shaky, and she laughed, then leaned against his shoulders with her arms stiff. He raised up and looked at me in the eye. He scowled at me, and I beat feet to my bedroom, leaving the door open. A few minutes later, I heard them come up the stairs, turn down the hall, away from me, and go into Mom’s room. Her door was closed when I peeked into the hall.
I plopped down on my bed and heard nothing more. I was trying to, but they were being very quiet, or the sound insulation was great. I suspected the sound insulation was fantastic. Dad had built this house about 10 years ago when his construction business was well established. He seemed to build things right.
One hour later, Kathy came pounding up the stairs. She came into my room, and I gestured for her to keep quiet. She gave me a puzzled look as I got off the bed and motioned for her to follow me. We tiptoed downstairs and through the kitchen to the garage. Their clothes were still on the floor! Kathy gasped, looked me in the eye, and said, “NO!” I grinned and nodded, mouthing yes to her.
I went over, closed the door, and proceeded to tell her the whole story. I left out no detail. Kathy was staring at me the whole time, shaking her head once in a while and squealing out a soft, “No!” when I told a particularly juicy point. I pointed to the chair seat, and it was puddled with smeared cum, sweat, and pussy juice. She squealed her exclamation again and was laughing.
“I think they are still up in her room fucking!” I told her.
“They have been up there for an hour!”
Grinning, Kathy muttered, “Guess Mom was horny, huh?”
I told her that was an understatement! “Look at this!” I said as I opened the door to the kitchen and pointed to my drying cum on the door and floor. It had run down the door and puddled on the step. It looked like someone had stepped in it and tracked it into the kitchen. Mom or Chuck! If it was Mom, she probably knew who did it and what it was! Oh man! I could be in deep doodoo!
Kathy and I didn’t know what to do. I cleaned up the mess on the door and floor. Kathy fixed us some sandwiches, and we sat in the kitchen eating. Then, we went into the family room, off the kitchen, flopped on the floor, and stared at the TV. I had no idea what we watched. We were waiting. About two hours later, Mom came breezing down the stairs wearing jeans and a long-sleeved shirt, said “Hi”, and went into the garage. A few seconds later, she came back with their clothes in her arms and without a word, went back upstairs. About fifteen minutes later, they both came downstairs. Chuck was red-faced and looking at the floor. Mom was smiling. She took Chuck’s hand and pulled him into the family room. She took him to the couch, and they sat down facing us. Kathy and I were sitting bolt upright on the floor, staring at the spectacle in front of us.
“Well, I guess you know we had sex.” Mom said matter-of-factly. We both nodded.
“Does it upset you?” We both shook our heads no.
“Do you know it may be against the law for me to have sex with a seventeen-year-old?” We both nodded again. Chuck was just staring at Mom as she talked.
“I don’t know that it is, but if it is, I could go to jail.” We shook our heads no at that one.
“Can we keep it a secret?” Even Chuck nodded at that one.
“Good! I don’t regret what we did for a second! It was the most fun I’ve had since your father died!” She was smiling and stared into Chuck’s eyes for the “don’t regret” part. She looked at Kathy and me, waiting for a response.
I was the first to speak, and I told her I was happy for her and Chuck. I told her that Chuck had had a crush on her since we were little. He nodded to her when she looked at him. I told her that she could do what she wanted, when she wanted, and I’d help any way I could. I wanted her to be happy; my eyes teared, and my voice cracked when I said that. Kathy was up and hugging Mom when I managed to look up again.
“Anybody hungry?” Mom asked. Kathy and I said we had eaten.
“Well, we’re starved!” She was looking at Chuck when she said that. They both laughed, and Chuck blushed. Some private joke! Kathy and I looked at each other and shrugged. Mom fixed sandwiches and Cokes. They ate quietly in the kitchen while Kathy and I watched them. Once in a while, they would look at each other, and smiles would spread between them. Geez! I expected them to start playing footsie or something.
At last, they finished, and I suggested we finish the measurements. We trooped into the garage and started again. This time, I only had to remind them twice to pay attention. We finished in a few minutes. Mom was looking at Chuck when she announced they had to talk in private. She took his hand and led him into the kitchen. Kathy and I looked at each other and shrugged. We put things away and went into the house. They weren’t to be seen. I signaled to Kathy, and we went up the stairs. The door to Mom’s room was closed. I tiptoed up to the door and put my ear to it. I couldn’t hear much, but what I did hear led me to believe they were fucking again. Kathy poked my shoulder and gave me a quizzical look. I signaled what was going on by poking my forefinger through a circle made with the thumb and forefinger of the other hand. She smirked and pulled me away. We went into my room and closed the door. She fell into my arms, laughing.
“Way to go, Mom!” She almost shouted, and we both laughed till the tears flowed.
“God! She must have been way too horny! I hope she doesn’t fuck Chuck to death!” She was laughing so hard she got the hiccups. It was too funny for me, and I ended up sitting on the floor. Kathy fell on me, and we rolled around on the floor, laughing till it hurt.
We finally calmed down, and I asked Kathy to read the coordinates from Mom’s measurement to me. We finished in short order, and I printed out Mom’s drawing. Then, we compared it to Kathy’s. They were amazingly similar. The distance between the eyes and the angles between the eyes, ears, and nose were practically identical. Mom’s ears were a fraction of an inch larger than Kathy’s. Maybe this would work. Kathy wanted to snuggle with me, but I convinced her that now was not a good time. She pouted for a minute, and then we went downstairs.
It was three more hours till they came out of Mom’s room! Chuck was smiling sheepishly, and Mom looked ravishing! She had put on a spaghetti strap dress, and there was no bra under it! Her tits swayed and jiggled as she came down the stairs. She was barefoot and fresh-fucked! Her makeup was perfect, and her smile was the most wonderful I had seen in my dim memory. I know I hadn’t seen her smile so contentedly in years! Sex must be good for you.
“Whoa, Mom!” Kathy chortled and jumped up to give Mom a hug. Mom looked over at me, and when she smiled at me, I winked. She acknowledged by closing both eyes for a long second, and then she gave me that glowing smile I hadn’t seen for so long.
She looked at Chuck and nodded toward the phone.
“Chuck is staying for dinner.” He had already started dialing.
“Is he staying for breakfast?” Kathy chortled. Mom gave her a shocked look, then they both started laughing! Chuck clasped his hand over the mouthpiece and told them to shush. He told his mother he was staying for dinner and hung up.
“Wanna sleep over tonight?” Kathy chortled as she looked at Chuck. He looked at Mom, and she shook her head.
“Oh no, you don’t. Tomorrow is a school day.” Mom reminded us. A flash of disappointment went across Chuck’s face.
“Maybe next weekend?” Mom said it airily, but there was a hint of a serious question behind it. Chuck looked into her eyes, questioning her. She nodded to him, and his smile would have lit a city. Well, I guess I knew what they would be doing all weekend! Kathy looked at me, then we shrugged at the same time, and we both started laughing. Mom looked at us and blushed.
“Well, I guess I can if I want!” She said with a pout.
“Only if Chuck can hold up!” I piped. Kathy was laughing hard again, and I joined her as we rolled around on the floor. Mom and Chuck were looking at us as if we were spoiled children. That did it. We started laughing even harder. Tears were rolling down our faces when we finally came up for air.
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