I was a horny 15 year old in the late 80's when wrestling was big. I was on my high school wrestling team, but wanted to become a professional wrestler. My parents both worked and were very strict. After school my 13 year old sister and I were to come home, to do our chores and homework.
My sister and I were very close and she volunteered to let me try some wrestling moves on her. We would go to the garage, put down the mats and wrestle. At first I was just trying to practice my techniques, but the more and more we wrestled the hornier I got. At first when I would grab her breasts or her crotch she was uptight, but she got used to it. She also got used to feeling my dick rub against her.
One day I asked her to try a move with me. She laid on her side with her legs wrapped around my waist. I said that I would try to get loose. In trying this, I forced her to roll on her back and her leg hold slipped to below my butt. I was now mounting her with my dick pointing straight up in my wind pants, rubbing against her crotch. I pushed against her breasts with my hands. I pretended to try to free myself which just caused more friction. All of a sudden I let go and came in my underwear. It was the best feeling, but I was so embarrassed that I broke free and ran to my room.
The next day when we got home from school, my sister asked if we could wrestle again, and could we try the same move as the day before. It wasn't long before she realized what I was doing, and she liked it too. She would even wear a bikini like the female wrestlers did and even got me to wear one of her bikini bottoms so that I looked more like a real wrestler. This continued for about a year with the touching getting more intimate and her top 'accidentally' coming at times.