When I was about 13 or 14 my family had planned a trip to an amusement park with some of our friends. We were all staying at our house the night before we were to leave so space was limited for sleeping. My sister and I shared my bed and in the floor around us was 2 of my brothers and 2 of our friends. Everyone was asleep except my sister and I and we were talking about our upcoming trip. She is a little older than I and she had startd filling out real nice. As we talked I rolled over onto my said and when I did I accidentaly grabbed one of her boobs. She yelped a little and I said I was sorry but she said it was ok. After this our talk turned a little more sexy and she asked me if I had ever seen any tits before. I didn't want to tell her I had peeked in on her in the bath a few times so I said no. She said I could look at hers if she could see my dick. Of course I jumped all over the chance. All we had was a little light from the window but when she pulled her gown up all I could see was nipple. These nipples were amazing. Long, pink and begging to be sucked. I was mesmerized when she said it was my turn. Being the age I was my dick got hard when the wind blew so you can imagine how hard it was when I pulled my shorts down and showed it to her. I wasn't as big then as I have wound up being but I was still ok with the size of my dick. So there we were me staring at her tits and her looking at my dick. I asked her if I could touch them and at the same time she grabbed ahold of my dick. I was in heaven. I was squeezing her tits and pulling her nipples and she was touching my dick. I don't think either of us knew what we were doing but neither of us cared. We kept it up for a few minutes when she asked me if I wanted to put it in her. Well hell yeah I did. I said yes and she eased toward the middle of the bed while taking her panties off and I eased up on top of her. I wiggles around trying to figure out what I was doing without looking like a total fool when I felt the top of my dick slide into her. We both froze for a few seconds before I ask was she ok and she said yeah to go ahead. I kept pushing in until I felt what I thought was the bottom. In hindsight I know now that it was her hymen and that I was about to take her virginity. If we had either known what we were doing I think we would have stopped before it went that far. Instead, after sliding in and out a few times I felt something give way and I went in deeper on the next stroke. She wimpered some but I didn't stop. I was giving her all I had while trying to not make a sound. After a minute she was ok again and I was about to cum. I told her I was getting close and she said to pull out. I told her that when I played with myself and came nothing came out so I just kept fucking her. After another few seconds I came with my dick burried deep inside my sister. We laid there for a second before I rolled off of her and we slid our clothes back on and went to sleep. I woke up the next morning scared to death that she was pregnant. I even asked her at the park if she thought she had gotten pregnant. Looking back now that was kind of funny thinking she would have known she was pregnant just a few hours after her first fucking. We fooled around some more after that but never fucked again. Mostly just a quick feel or skinny dipping together. Oh, she didn't get pregnant by the way.