I'm not gay, and this is the ONLY time I've ever had a male/male experience. But, this happened when I was 18, which was two years ago.
My friend and I were hanging out one day like we usually did. Both of us being virgins, we are saving our virginity for marriage, which is a good thing. Therefore, we just talk about sex A LOT. Well, we were hot and horny one day, and were talking about masturbation, when all of a sudden we decided to compare penis sizes. Hey, I saw nothing wrong with this. We are both circumcised and at the time were around six and a half inches hard. Our balls were the same size, and we had about the same amount of pubic hair. So, we shared a lot in common, and we thought that was cool. We didn't dare touch each other, and didn't want to. We just needed to get off.
So, we watched each other jack off while sitting next to one another. We jerked off onto a towel on the floor. It was fun, man. I won't lie, but that's the only m/m experience I've ever had. I don't know if it will happen again, and I don't really care. I just figured I'd share that story.