When I was younger my mother gave me the book Our Bodies Ourselves. I guess it was my parent's way of giving me 'the talk' without actually doing it. The book was filled with supposedly real letters from teens concerning puberty along with drawings of everything from breast development to public hair growth. One of the subjects in the boy's chapters was about wet dreams. It didn't really explain exactly what an orgasm was but it said that a wet dream was caused by ejaculating in your sleep while having a really sexy dream. I was curious what this was all about.
I never actually had a wet dream. My first orgasm happened while rubbing my crotch against a small bean bag chair when I was 13. I didn't ejaculate very much semen but I had a pretty good idea what had happened. Needless to say I started masturbating the very next day. Back then I could have three or four orgasms a day; my hormones were raging. I would look at a porno magazine that I had found and fantacize about the naked women. Because I was pretty inexperienced when it came to controlling the stream of my ejaculations it wasn't long before the pages of that magazine were stuck together.
When I turned 14 I went to summer camp. Late at night I would pull my knees up and jerk off inside my sleeping bag until I came all over my belly. I don't know what the other boys were doing but I expect that it was something similar.
As I got older and started dating girls they would rub their crotches on mine until we came. I enjoyed the orgasms but I had stopped wearing underwear by then and I didn't particularly like coming in my pants all the time. I had one girlfriend that would rub her crotch furiously on my leg until she had multiple orgasms. She was only 13 so she must have had an early start.
I never really changed positions much; I would generally lie on my back and ejaculate all over my belly. As I got older one of my girlfriends turned me onto a very sensitive spot in between my scrotum and my ass that, if pressed hard, would delay the ejaculation even after my orgasm had already started. There was a throbbing sensation that you could feel when the orgasm started and when the pressure was released, I would spray sperm all over my chest (or in her mouth). It made the orgasms very intense.
I haven't talked to too many of my girlfriends about masturbation but I think it's safe to assume that they were all doing it by the time they met me. I think they were too embarrassed to bring it up with me but I bet that some of them would have been curious to watch me do it in front of them. I know that I wanted to watch them do it to themselves.