I will remember this night forever.
One Friday after school I asked my best friend Jake if he could spend the weekend at my house, and he said yes. We were both pretty small little 13 year old boys, we were both about 4' 10' tall and weighed around 95 pounds.
We went over to my house after school and went swimming in my pool. After we were swimming for about 20 minutes Jake went to get out of the pool, but the weight of the water accidentally pulled his swim shorts down, revealing to me his cute little butt. Now I'm not gay or anything, but when I saw his butt I got an instant hardon. I didn't want to appear gay though, so I just said, 'Haha, nice butt Jake.' He just said shut up and went inside.
Later that night when we were sleeping I was talking to him, and I really wanted to masturbate with him. We had been inseperable best friends for almost 9 years, and remain so today (now 18), and we loved each other so much that I figured I could talk about anything with him, so I asked him if he knew what masturbation was. He said he had no idea. I then asked him if he knew what an erection was. He said he did. I asked him how he deals with his erections if he doesn't know about masturbation, and he said he just waits for them to go down. I told him that I was going to show him something better to do with them, and he said ok.
I pulled his shirt off and started to rub his belly, then I started to tease his nipples and rub his back and tummy all at the same time. This gave him an instant erection. Then I started to grab his butt and I massaged his thighs. Then I slowly undid his belt aand pulled his pants down, leaving him in tighty whities. I then started to slowly massage his inner thighs making my way to his penis and then I fondled his testicles, which made him convulse in pleasure. I gave him a big hug and told him he'll be fine, then I pulled down his underwear and grasped his rock hard member. I got him so he was sitting on my lap and I started to slowly stroke him. After about five minutes of this he was breathing really hard, so I took my finger and put it in his butthole and started to move it around while I was stroking him, this made him instantly blow a huge load right in my hands, and the pleasure was so much for him that he almost started crying, so I just laid him down and hugged him until he was all better. Once he calmed down I asked him if he would do it to me, and he did.
That's the story of how I taught my best friend to masturbate, and we still do it together all the time.