This happened when I was thirteen years old.
I was in gym class one day, and the coach had to leave as soon as class started. He introduced us to the 'sub' who was taking over for him, then left.
The 'sub' told us to play quietly in the gym until class was over, then went into the coaches office, and shut the door. After playing some basketball for a while, my friend, (who I will call Marvin) called me off to the back of the gym. He told me to wait five minutes and join him in the storage section. He said he had something to show me.
When I got to the storage area, Marvin wnet to a volleyball pole, put his hands up on it, and started humping his crotch on it. When he had done this for a couple of minutes, he turned toward me, pulled his gym shorts down, and showed me his hard cock.
When I saw his thick, six inch dick, I was erect in an instant. He asked me if I wanted to touch his dick. I answered him by wrapping my hand around his swollen cock head, and squeezing it. He moaned and pre-cum dribbled from his hot penis onto my hand. He asked me to jack him off, and I was only to happy to grant his request. After ten minutes or so he shot his huge load of cum on the floor.
Marvin then told me to pull my shorts down. When I did, he got behind me and pulled me back until his half-hard penis was touching my naked ass. He took my four inch cock in his hand and jacked me off. With his dick touching, I came in record time.
Marvin and I masturbated each other all through our school years. We also sucked each other's dicks, but I will write more on that subject later.