“You must have had a fun date tonight,” I quipped as I drove to full insertion on the first stroke. Her pussy had the familiar silky slickness of fresh semen.

“Yup. One of my favorite guys. Big cummer and stays hard for a second go. Hope you can get some traction,” she replied with a big grin.

It was a routine we had developed during the past six months since Sis had gotten on contraception. When she turned sixteen, the age of consent here, we had gone beyond playing “doctor” but short of penetration. She’d heard some stuff about screwing from girlfriends. I’d been laid a few times by an older cousin at a family reunion and I shared the story with my curious Sis.

Then the watershed moment about two months after her birthday. The older single father she babysat for came home one night pretty “lit”, dropped off by drinking buddies. She decided he couldn’t safely drive her home so texted our mom. He stripped in his bedroom and lay on top of the covers naked.

His pecker was half hard and exposed when she went to check on him. Having thoroughly explored my male parts, she was intensely curious about the differences in that tubular organ. He didn’t respond to her voice so she reached for it. Of course, it stiffened with her touch. His balls were bigger and hairier than mine but she left them alone for now.

As it lay, long and hard, on his belly she took the next step. How would it taste? Maybe like piss since he probably hadn’t washed it. She’d tasted mine right after holding it when I peed so that wasn’t too bad.

It was a mouthful, a little thicker than mine. But it woke him up. He lay still for a bit, enjoying the feeling and the view of the top of her head. Then he said quietly, “This is sure nice to come home to.”

Sis pulled herself away, blushing bright red, “I’m so sorry! I didn’t think you’d wake up.”

He laughed a little, “I’m damn glad I did. So tell me why you were giving me a blowjob. A good one, by the way, and something I rarely get.”

Sis knew him well enough that she could gradually open up about her teenage curiosity. How she had explored a bit with me about this mysterious and interesting activity called “sex”. He was non-judgmental and asked some questions that kept her talking. His rod softened, showing he was concentrating on her.

Then he spoke gently, “Is there anything I can help you with or to learn? You can touch me all you want. It feels really good. I’d like to see your body too, if you’re not too shy. It looks really nice.”

Sis got kind of shy but was very flattered. She said, “Would you like to see my breasts? They’re kinda small but my brother likes them.”

“Of course! Maybe you’d let me touch them. After all, you have touched my special parts.”

They explored each other’s bodies for a while. Then Stan, the guy, said, “You can see I’m aroused and I think that you are too. Your nipples are standing out very hard.”

Sis nodded, “I’m getting a tingling down there. I get that way with my brother when he kisses my privates.”

“Oh, can I do that too. It’s been a long time and I think it tastes so good. I know how to make you have a BIG tingle.”

She was enjoying this a lot but a concern showed on her face, “I won’t get pregnant, will I?”

Stan opened his eyes wide, “What kind of sex education did you have?”

“It was at school. They had diagrams of the parts of men and women. They told about the eggs and sperms but not much about how they got together. They mostly said to us girls that we must never let anything inside our vagina because we would get pregnant and get diseases. Keeping your knees together was called ‘celibacy’.”

Stan smiled, “I’ve been married so I know quite a bit about sex. If you want, I’ll teach you a lot more than they did at school.”

Sis considered it for a minute and brightened, “I’d like that but I don’t want to get pregnant.”

“Of course not. Do you remember that it takes both an egg and some sperm to do that?” She nodded. “Well then, birth control is simply making sure that one or the other isn’t around during sex. Then it is just for fun, and you already know it can be a lot of that.”

He continued, giving her tit a gentle squeeze, “Right now, you might have an egg ready, although that happens for only a few days during your menstrual cycle. However, I have no sperm. After the kids were born I had a simple operation that stops them from coming out of my penis. Therefore, I can’t get anyone pregnant.”

Sis was wide-eyed, “Wow! So we could fuck and no babies?”

“Yup! And you can’t tell the difference either. Interested?”

“Sure! How do we start?”

“Get all the way naked and let me taste you. We’ll go from there.”

She had the biggest orgasm of her young life when Stan applied his skilled mouth to her pussy. She muffled her cries to keep from awakening the kids. “Oh My God! I didn’t know my body could do that!”

Stan smiled, “There are lots of things you don’t know yet. Are you ready to see what a penis feels like inside?” She nodded.

He put her astraddle his waist and showed her how to rub her slit along his shaft. It was swollen and dripping.

“Are you ready to put it inside? It might hurt a bit the first time.”

Sis replied, “I don’t think so. My brother and I have been putting things up me and something broke. Is that what you are worried about?”

“Yes. Now rise up a bit and I’ll line my cock up with your opening. OK, now come down slowly. There. Just move up and down gently until it pops inside. Good. Now more and it can gradually open you up.”

She had a wondering look on her face as her pussy lips made first contact with Stan’s mushroom head. It changed to surprise as the head popped inside and then bliss as more and more of the shaft stretched her virginal tissues. When she finally bottomed out, she looked at him and whispered, “I’m a woman and I love it!”

He held her hips and showed her how to move. She caught on quickly so he focused on her young firm tits. She figured out how to get her clit stimulated and orgasmed. Finally, he could hold back no longer.

“I’m going to shoot my cream inside you. Be still and let me make it happen.” He thrust a few times and groaned as his long-held load found a place to be.

“I feel it. It’s so warm. Thank you.”

That was the beginning of Sis’s real sex life. She had learned about safe days and when she got home from Stan’s it was only a few days before her period. They were quite regular.