This happened when I was 15 and had been into the pleasure for about 8 or 9 years.
I was about six when I first noticed that my pecker could get hard, and if I rubbed it I got a tingling feeling in my nether parts. I progressed from humping to rubbing the head on my leg, and finally jacking with my fist wrapped around my penis. By the time I was 15, I had a respectable seven inch long hard and six inch girth. I went to an all boys school which emphasized physical fitness, so we worked out every day and showered afterward in an open shower room where everyone saw the nude appearence of all the others. There was a lot of ribbing going on in the shower room about how much each of us masturbated, and I was usually the butt of the jokes since any experienced player of the upright organ could tell from their own experiences who was an excessive meat beater. I always turned the jokes off by replying to the question of how much I jacked off with about half as much as you do.
My friend Bob without my realizing it was taking all this in with great interest, so when he invited me to spend the weekend with his family, I accepted without giving the invitation much thought. When I got to his house, I learned that from saturday morning until sunday afternoon all of his family would be visiting his aunt who lived about fifty miles away. We were invited to go along, but Bob suggested that we decline. I agreed with him. That night after supper we went to his room, and began watching TV, and playing cards. After a while, he suggested that we play strip poker. I agreed, and when we were both down to our underwear and socks. The HBO channel was showing a movie with a lot of naked girls. Both of us had hards, and Bob casually asked me how long my thing was. I told him it was 7 inches, and asked him how long his was. He said that it was 8 inches. I looked surprised, so he went to his desk, got out a ruler, and confirmed its size. I was impressed that a 15 year old was that big. Then he asked me if it were true that I jacked off as much as the boys in the shower room claimed, I admitted to an average of three times a day, he said that he had to get off, and invited me to join him. I agreed, but asked for lube. He got out a bottle of baby oil, we lubed up, and started jacking. It took about ten minutes for me to have my first orgasm, and his followed a few minutes afterward. When we came down from our highs, we both asked how long the other had been into it, and he learned that for me it was 9 years old and for him, I learned it was just about the same. Then he admitted that he invited me knowing that he would have the house to himself and wanted to spend the weekend jacking off with me because from all the talk he heard, he assumed that I could milk my willy dry as he planned to do his. We fell asleep about 2 o'clock, woke at 5, did the first JO of saturday, and planned to do as many more as possible with about two hours between sessions until we couldn't go any more. By midnight saturday we had done 10 jackings, after the first few our peckers were not quite dry, but just oozed a little come when we orgasmed. Our peckers looked like they were boiled, mine looked worse since I wasn't circumcised, and my foreskin was swollen to at least three times its usual thickness. We slept until about 8 sunday morning. When I went to pee, my thing was so sore that I could hardly touch it, and when I peed it burned. Bob asked if this was the most I ever JOed. Since we had done it 11 times since friday, I answered no since I had done it as many as 15 times. Bob was fascinated with the way I held the foreskin back so when I came the come cleared my head just like his circumcised pecker did. We did it one more time sunday, and both of us had to quit. Then we started worrying how our peckers would look after gym monday. They would obviously look well jacked.