I didn't know much.
When I was 15 I met a girl who had come to our town for part of the summer. She was exactly my age and we really hit it off well in every aspect. It was a fairly platonic thing for me at first because I was so late maturing. I hadn't had an orgasm until I was 14. She was really nice, had a nice body, pretty face and kind of sheltered. She was the second of three daughters and resentful of the other two, one four years older and the other one year younger. We enjoyed getting off by ourselves to a movie or swimming, but nothing too exotic.
This changed when I agreed to move a 16' sailboat seven miles to our harbor for a friend's father. We got there at 5:00 and set off, but the wind died fairly quickly as the sun was setting. There was fog laying not far off shore and after two hours and a couple of sodas and sandwiches we had made barely two miles along the shore. But at this time she announced she had to pee. As you can imagine there is little privacy for something like that so I said I would turn my head while she used the bucket and we would throw it overboard. I said we all have that to deal with at some point. So she proceeded to drop her trousers while I turned away. As I heard that wonderful spraying sound she tooted. I naturally turned my head, caught a quick glimpse and started to roar. She got mad but I couldn't stop laughing. I did say that we all do that, it's not a big deal, but the image of her wonderful fanny with a little glimpse of hair poised over that bucket stayed with me. We were able to catch a tow from a passing open boat and ended up at 9:00 on the mooring. On the way over I kidded her a couple of times by making the tooting sound. She grinned each time and defended herself.
A week or so later we had gone for a short walk up a nearby hill on a Saturday afternoon. It was misty and not likely too many people would be out then. As we walked up, I was behind her and enamored by the sight of her behind. I said what a wonderful sight - it just struck me how beautiful her behind was in the white shorts. So she said what are you seeing? I said well from this view I can only see your aft end and I liked it better without the fabric. Again she grinned as she reacted fairly quickly and said, well if you have seen mine, I haven't seen yours or any other guys, so its not fair. I want to see yours, too. Gosh, I was overcome at having started this thing and not ready for this. But my cock was ready and it had sprung to attention at once. She said if we go off the trail you could let me see you, too. She was adamant that we do that and I kind of went along with it wondering what it would lead to.
As we walked off about 200' behind some boulders she said now its your turn and argued how mean I had been about the tooting and showing her stuff. So she reached for my belt and was getting a bit aggressive, so I did it myself, charmed that she actually was so interested. As I turned away, I dropped my pants and then undies so she had a clear view. It was so exciting to be partially exposed like that. At this point she said that her friend Sheila had said boys have interesting parts, too, and shoot white stuff. She asked if I knew about that and I said yes, so she asked to see the front, too. Without turning, I asked if I could also see hers and she was very blase about it and said sure.
So I turned slowly toward her with my cock at attention. She was transfixed by it and asked where my testicles were. I said they had pulled up into my body for protection but if she felt down there she would find them. She did exactly that and said, oh, I do feel them. Can I feel your penis and I said yes. So she wrapped her fingers around it and I immediately shot my load into the air about 2'. I couldn't hold it at all. She shrieked and said that was so wonderful. I said not to let any of it near her as she could make a mess or get some too near her vagina and we would have a real problem.
She did keep the promise and show me her bush and let me smell it. I was caught for life by the intimacy of it all. The open sharing and smells, etc. Only after I married at 24 did I learn girls can jerk off too. What a loss. Today that would not happen.