My first experience that was in any way sexual was when I was 5 years old and in kindergarten. My best friend (who was also 5) at the time and I would go into one of the walk-in closets in his house, and we'd pull our pants down and tell stories about how our families had gone to nudist camps--only at 5, I misunderstood and thought they were called Bermuda camps. Neither of us, of course, had gone to any such place, but we talked endlessly about it and made up stories about our older sisters who were naked at the camps too. Telling the stories got us both hard, so we must have understood some sort of sexual component to it, but, I don't remember he and I ever touching each other. I don't remember us ever playing "Bermuda Camp" after kindergarden.
Some time in grade school--I think it started in fifth grade and continued into sixth, I would stay over night with various friends, and we would fool around. I remember we would play with each other's dicks to make them hard, and we would sometimes put our mouths on the other guy's dick, and we lay on top of each other and put our dicks between each other's butt cheeks, though we never penetrated each other. We never came either. Totally unrelated to this sexual activity, I had discovered that if I lay face down with my hands against my crotch and pressed really hard against my dick, I would get this really intense feeling. I didn't correlate it with anything sexual--I just knew it felt good. I discovered this probably around 4th grade. I did notice that if I pulled my pants down and pressed skin on skin that I'd get that feeling faster and more intensely. I usually did it in the bathroom and I found that if I left the door open, it was even more exciting since there was the chance that someone could find me--I was thrilled by the risk. One time my sister (2 years older) did catch me and she was like, "What are you doing?" Quick 5th grader that I was, I said, "I was waiting for you to come spank me." My sister thought I was nuts, but finally said, "Okay, come here." Then I weirded out and said, "No, too late--I changed my mind" and I pulled my pants back up.
I was playing Truth or Dare with a buddy of mine--must have been around 7th grade--and he dared me to rub up and down on my dick until I got a "neat feeling." I had no idea what he was talking about. So we both did it. He got the neat feeling, but I never did. Not long after that I woke up in the middle of the night and I heard, for the first time in my life, my parents having sex in the next room. I immediately realized what they were doing--their bed springs squeaked--and it made me horny and hard. I remembered my friend telling me about rubbing up and down on my cock for a neat feeling, and so I jacked myself up and down with my hand, and suddenly I got that neat feeling--the same one I'd been getting since I was really young, and I realized, ooooh, that's an orgasm. I was too young to shoot anything, but believe me that discovery set off my constant jacking off.
I was 13 the first time I had an orgasm with someone else. A buddy of mine and I were sitting in our friend's "fort" in his back yard and we started jacking each other. We didn't talk about it--we just sat and did it. I had an orgasm (still didn't shoot anything) and stopped jerking him, and I think he must have had one too as he stopped jacking me and we put our dicks away and just kept talking like nothing ever happened.
My first blowjob came at 15 when a buddy of mine and I got drunk in his sister's basement while he was babysitting his nieces (they were asleep). He told me he'd found his brother-in-law's porn collection, and we were looking at his hardcore magazines (straight stuff), and we were talking about how our dicks were like this guy's or that guy's and we pulled our pants down to show each other, and we were both hard, and he asked me if I wanted a blowjob, and I said, sure if he wanted to. I shot in his mouth, but I was embarrassed that he'd think I didn't shoot very much. I had jacked off earlier in the day, so my 15-year-old load wasn't that impressive, but especially after having shot off earlier in the day, but my friend didn't seem to mind and he knew when to stop, so I figured there was enough cum for him to taste it to know I'd shot. After that I didn't have another sexual experience with a guy until I was 19 (another blowjob).