First of all I would like to say that both my cousin and I are straight. I was 16 at the time, and he was 14. During a sleepover at his house, we had talked a lot about sex and masturbation, and asked each other truth or dare questions. We started asking each other to do erotic things, and I felt my dick getting hard.
After a while, I asked him if he wanted to jack off. He said sure and we got naked in the bed and started slowly stroking our cocks. I then reached over to grab his cock and pumped it gently, while he did the same. This was the best feeling I had ever felt. I felt my dick get harder from the intense feelings. We tried to keep our moans low so we wouldn't wake his parents.
I then climbed over him and begun pumping away at his throbbing cock. I massaged and tickled his balls, and started rubbing his inner thighs, making him shake all over. After about 10 minutes, we switched roles, and I felt I was in heaven. He used my precum as lube and and started stroking. To my surprise, he started licking and sucking my nipples, and it felt awesome, so I did the same to him.
We played around with each other for about an hour, trying our best to hold our juice in, until he asked me to get into the shower with him. I said yes quickly, and we got into the shower. We used shampoo and bodywash to lube up our cocks, and started pumping away. It felt awesome to be jacking off with someone under a steamy shower. Within minutes, hot ropes of cum shot out and we covered each other with our juice.
Since that day, we would have at least one jack off session everytime we had a sleepover.