I began to masturbate at about the age of 12. Of course, once I did start I did it all the time. When I was 13 we went on a vacation to visit my mothers sister. She had a daughter my age.
She invited me to go with her to meet a male friend of hers from school. We walked around and ended up in a field. Then she said she and her friend always play a game called, 'You show me yours, and I'll show you mine.' I got an erection just thinking about it. When she asked if I would like to play, I said 'Sure.'
She pulled down her jeans revealing her panties. Then her friend did the same and I followed suit. It was not hard to see the outlines of hardons for both her friend and I.
She told her friend to go first and he pulled down his underpants revealing a very stiff erection. She went next. I had never seen a naked girl before. Then I pulled down my underpants. I was SO hard. 'Very nice size,' she said.
Her friend began to masturbate as he looked at her. She removed her top revealing small, just forming breasts. Sitting crosslegged, I put my hand on my penis and began to masturbate going quicker and quicker. She got up and came over and let me feel her breasts. Then, looking at and touching my first live naked girl, I came quickly. I came all over my legs and hand. The other two also masturbated and her friend soon came when she touched his penis. She played with herself and then said she had come but, of course, it was much more evident for us guys. It was such an intense orgasm for me. I had to clean up with my underpants and then put them back on to go back home.
I have never forgotten that day and the great feeling I had. Masturbation has always been a major part of my life since.