I was Fifteen at the time and my friend Mark who was then fourteen had came to spend the weekend with me.
By this time we had already had a mutual masturbation thing going on since we were twelve. We had mostly done things in his house because unlike my parents his were out of the house much of the time leaving us hours to do what ever we felt like. In my house it was the complete opposite because my Mom was always there and if I had a friend over she was constantly checking on us.
So that night Mark wanted to 'play around', he had brought a porn magazine with him and all he wanted me to do was sit down, look at it and jack off with him. He said it was stupid to jack off alone but I was so scared that my mother would catch us that I didn't dare pull my pants down or even take my erection out through my fly.
After rejecting Mark's mutual jack off invitation It seemed he had given up but later that night he told me that everybody else had to be asleep and that we would just jack off real quick and quiet, clean up our cum and go to bed.
We started off that way both of us sitting on a large bean bag chair looking at the magazine and stroking our erect penises.
For those that like descriptions, I'd say 5.5 inches for me and maybe 6.5 inches for Mark, give or take. He was not circumcised and I was, he had black pubic hairs and I had brownish blonde.
But soon after we were both humping the bean bag chair and we both ejaculated one after the other. We were close enough to each other that some of our ejaculate mixed together.
We pulled up our pants got in bed and went to sleep, we were awakened in the morning by my mother who was standing their pointing to the bean bag that we forgot to wipe off. By this time our semen had dried but it was still noticeable against the black material of the bean bag chair. She asked in an angry tone 'What is this?' and I nearly died, Mark was also in shock.
I was trying to figure out in my head what I could possibly say to my Mother besides the truth which was that Mark and I were humping the bean bag and then ejaculated on it.
Luckily my Mom said 'Don't ever bring food in this room again' and then she went on a rant about how I don't appreciate the things she buys for me. We were never so happy to be lectured on appreciating things and keeping food out of the room.
From that day on when we were at my house we kept our penises in, at his house it was playtime.