I think I started jacking off around 12, having overheard some guys in the gym locker room talking about how to do it. I tried it and was amazed when I had an orgasm; I recall thinking that if sex was anything like that, my wife would have 100 babies. I also recall that when I was about 13, I was shocked the first time I shot a load into the palm of my hand (I was using a top or "eagle's claw" grip). Wasn't sure what it was for a couple of seconds.