Teen Brother-younger Sister

My sister is five years younger than me but I don't remember our exact ages at the time. We were not real close but close enough to do a little fooling around near teenage years. The first time we went on a family camping trip. My sister & I were teamed up in the bed of our pick-up truck to sleep under a protective tarp. It was totally dark so we were afforded a degree of privacy as we prepared to sleep. I started casually letting my hand land, touching her leg or arm for a short time to test weather she was willing to play. So far so good. She allowed her hand to touch me in different places. I rested the back of my hand against her orange sized developing breast. We were trying to be very quiet. Our brother was bedded down in the front seat of the pick-up. We continued, becoming bolder as we brushed our hands across crotch areas enjoying the discovery of being touched this way for the first time by another. I was the more bold one and she did not loosen or pull open her PJS. By this time my adolescent Penis was hard and I helped it poke out of the top of my PJs. We progressed trying to contain our excitement & increasingly deep breathing and squeals of surprise. Finally, my sis layed her hand across my crotch in significant contact with my Penis and stayed still just feeling the warmth and the incredible excitement of this intimate touch. I made the next move by flexing the muscle of my Penis against her hand. She was grossed out; and exclaimed Ooooooo! She pulled her hand away quickly and that wes the end of our play time for the evening. We had one other skinny dipping adventure with sis' friend & sister during which we had a lot of giggles. I started out real slow but have made up well for lost time. Would like to tell all if I get time to write again.