I just read the post 'Teaching Other Boys' which reminded me of a similar experience. Every time I read these stories I'm reminded of my own full repertoire of adolescent and childhood sex.
Mark's family and mine were the closest of friends. He was almost two years younger than I, so I thought of him as a hopeless child severely deficient in the secret erotic information and exotic pleasures I dearly treasured. This opinion was based on what I thought of as my advanced knowledge of penis pleasure. I had been jacking off since I was nine and shooting for about six months; consequently from my 13 year old world view, Mark was a little boy. I was soon to find how much I underestimated him. I kept my peter pulling strictly to myself not out of modesty, but because I didn't want publicity in that my mother was very straight laced. Her reaction to such news was an unwelcome unknown risk.
So much for the background. Our families decided to see a play which Mark and I had no interest in, so we asked if we couldn't wait for its end in the foyer of the theater. They agreed. Once outside, Mark began talking about the weekly nude swim we had with our fathers and brothers at the all male club which our fathers belonged to. He mentioned that I had matured a lot in the last six months, complemented me on my patch of pubic hair, and the growth of my penis. Then he began discussing how horny he got thinking about girls, and asked if I had the same reaction. I admitted that I had. Then he suggested that we go and sit in the car to continue our conversation. I agreed.
After another five minutes of conversation about girls, and their boobs and boys and their peckers, he asked if I knew how big my hard on was. I was a little hesitant to answer, but he weedled an answer from me. It was six inches long and five inches round. Then he asked if I had a hard on now. I admitted that I did. Next he asked to see it. I felt irresistibly compelled to let him see it, unzipped and pulled it out. Sensing that he had me hooked, he pulled his own four incher out, looked me in the eye and without asking, began to stroke my penis. I didn't stop him. That was the first time anyone else had touched my pecker for pleasure. Feeling hypnotized I just sat there until he told me to jack his penis which I did. This continued for a few minutes when I began to feel an orgasm comming on. I stopped him, got my handkerchief out, and jacked myself until I had a huge come. He exclaimed, 'God what a load'. Then began jacking his pecker furiously until he had his own come.
As we relaxed, he slyly said, 'Come over after school tomorrow, I'll be home by myself'. So began our mutual jack off sessions which lasted until I left for college. It kept on even after both of us were dating and screwing girls. Perhaps I'll post some of these events.