When I was sixteen, one night on my vacation my cousin slept over because his parants were on vacation in another country, my cousin is around the same age as me. My parents were away for the weekend too.
My cousin and me were home alone, we first watched TV till 23:00 hours, some dull science fiction movie. After the movie there was an erotic movie on. I had already seen the commercials about it, my cousin didn't know about it.
After about fifteen minutes the first erotic scene started. My cousin was watching with big eyes, he had never seen erotic movies. I was getting a boner and was getting very horny. After about 30 minutes, my boner was killing me, I told my cousin I was going to bed. In fact I was going to bed to jerk off because I didn't want to do that in front of my cousin.
I went to bed, took off my clothes (also my boxers) and started to masturbate. I was still hearing the erotic movie sounds coming from the living room and was getting close to my climax. I heard a sound coming from my door and saw my nude cousin, watching me, with a really big boner. When I saw him watching me I was getting even more horny then I already was and came in an instant. He was still watching me at the door.
I covered myself with my bed sheets and asked if he saw anything. He told me he didn't, but I knew he did. He got in his bed, an airbed and went to sleep. I turned and went to sleep too.
After about 20 minutes, my cousin was complaining that the airbed was leaking and he was lying on the floor. I told him he could join me in my bed, I was still nude. He said nothing and got into my bed also nude, with a huge boner. He asked me what I was doing when he walked into the room. I told him I was wanking, he never did that and wanted to know how to do it, I told him and was getting a boner again myself. He said he wanted to try it but didn't dare to do it, I then grabbed his penis with my hands under the covers and was jacking him off. He was a little scared, but after being jacked off for five minutes he grabbed my boner and was doing the same.
After about ten minutes he was saying he was getting a weird feeling in his stomach, I told him he was going to ejaculate. He stopped jacking me off and asked what it was. I yelled a little bit at him about don't quit jacking me off and I'll tell you. I told him about semen and cumming, he was very excited and came over my hand and spoiled a little bit on my body. When he came I was cumming too and came over his hand and my own stomach.
I walked over to the shower and cleaned myself, he joined me. After the shower we went to sleep again. The day after he was very shy and wasn't sure how to start talking about our wank sessions. Later that second night we wanked each other again.
That summer is a summer I will never forget, it was my first Male-Male interaction. But not my last.