When I was in high school, I had a friend my age named Dave, who I met through work. He went to another school, but had several mutual friends and we would see each other at work and sometimes party together on the weekends or over vacations.
One time during my junior year, he had a party at his house when his parents were away for the weekend. Nothing really exciting happened, but both Dave and I ended up making out with a couple of girls that Dave knew. This was pretty tame and far short of sex, but it was a lot of fun for me (I was still a virgin then). It was quite late when things started with the girls, and far too soon, they both had to go home, which meant Dave or I had to drive them because they were still 15. So the four of us piled into Dave's junker and Dave drove the girls home. Helen, the girl I was with and I, made out some more in the back seat on the way, but then we got to her house and she and her friend got out. I got in the front seat with Dave, and we began one of our late-night gas station coffee-stoked drives out into the semi-rural area around our town just killing time, which a number of us did quite often at that age.
We pulled off the road down a dirt lane and walked out into a field toward a small hill where we had ended up a number of times before with various friends, just hanging out and talking most of the night, as teenagers do. We flopped down in the grass looking up at the sky and just talked for a while about the party and Helen and her friend. I think we were both kind of worked up from making out with the girls earlier and I honestly don't remember exactly what Dave said to start it off, but we started talking about masturbating and after a little while, he asked with some hesitation if I wanted to masturbate with him. I remember feeling very relaxed but also horny and said yes.
We both pulled our pants and briefs down to our knees and laying side-by-side, began to masturbate together. We never touched each other, just ourselves, but it was very exciting nonetheless. I remember we both went very slowly, watching eath other and talking about how we liked to do it. Then we'd just be looking up at the stars, each stopping when he or I would get close to orgasm, then starting again once we'd calmed down. I think we probably masturbated for a good thirty or forty minutes before I finally said I wanted to come, and we both brought ourselves to orgasm at almost the same time, Dave reaching his while I was still in the middle of mine. Having waited so long, and doing it in front of my friend, too, probably, I remember my orgasm as being particularly good and I really groaned when I came, which made Dave laugh. Soon, he was coming too, though, so he started gasping and laughing at the same time, which made me start to laugh as I wathed him coming and trying to keep his orgasm going as long as he could, and then after we'd both finsihed our orgasms, we were laying there with our pants down and our hands and bellies all sticky and Dave saying 'Oh wow, that was good!'