When I was 13 I kept getting boners- I'd gotten them before, but it seemed like I was hard all the time and couldn't figure out why. One day in the bathtub I was laying on my stomach in shallow water pressing my dick against the bottom of the tub- again, I didn't know why. I flipped over and tried putting my arm (just above my wrist) against my hard dick pressing it up against my belly and using my other hand to apply a lot of additional pressure. At some point I accidentally slid my arm across my dick and got a "zing" sensation of pure pleasure- I didn't remember what I did to get that feeling but I was on a mission to figure it out real quick. A few seconds later I duplicated that feeling by using my wrist to slide my dick across my belly in one direction. After about two strokes, I had enough foresight to try some lube in the form of some soap- I lubed up my arm, dick, and belly, and tried it out. OMG!!!!!!!! I had no idea what I had just stumbled upon, but I was hooked for life from that second on. I rubbed my little hairless boner back and forth over my belly with my arm in uncontrolled jerky motions with the water splashing all around. It kept feeling better and better and I just got more intense rubbing it at high speed and taking short breaks. I would look at my hard dick and wonder why it felt this way? Why hadn't it felt like this before? I rubbed it like I hated it and finally had some intense pleasure as my young little body stiffened up for my first ever orgasm. I let it cool off a little and tried for a second round, but it wasn't interested- it felt like nothing when I rubbed it and I couldn't figure out why. I finished my bath and tried it again the next night.
The next night it felt terrific again to my delight and I rubbed the hell out of it splashing around and wiggling all over the tub. The funny part is that I thought I was the only human being on the planet who had figured this out, so I didn't need to be quiet about it- no one else would know what I was doing. I'm sure everyone in the house heard it... It was a mystery, why did it feel so good to do this, then as soon as I finished it I felt a little guilty, and kind of stupid for doing it. I loved doing it, but on occasion decided I would stop. No luck there, I'd get two or three days down the line and beat it half to death in a wonderful rub session better than ever. I did this for at least six months, and somewhere around age 12 I started noticing some goo in the bathwater when I was finished. The first few times I didn't give it much thought, but then figured it must be cumming from my dick. So the next time I rubbed it, I watched it shoot some nice thick streams of cum out at climax. I have always regretted using the tub for a jack location, because I would have loved to see the progression of minuet amounts of clear oozing out at the begining to thick, huge ropes of jizz blowing out several months later. Sometime along the jizz discovery phase I started noticing hair growing on my dick too. Again I didn't give it much thought, I just kept hammering my dick several times a week, rarely missing a day unless I was sick. At some point I graduated out of the tub, and started jacking with my hand in the bathroom. I rubbed it between my belly and arm for years after that on occasion though, just for a change of pace. I also learned that other boys were doing it too, and what that jizz wad was for. Along that period I discovered how looking at mild porn (All I could get at the time) enhanced my jacking sessions.