I was 14 when this happened between my best friend, Jeremy, and myself. We both live in the UK, and I am tightly circumcised (which is unusual in my country, apparently) with blonde hair and blue eyes. At the time, my penis was about six inches hard and I had a small tuft of pubic hair. Jeremy was also 14, and his penis size/pubic hair growth was about the same (though he was uncut). We also looked similar, and people often mistook us for brothers.
Anyway, on with the story. My friend was staying the night at my house for the first time, and we were about to go in my jacuzzi (which is an indoor spa). We were both in my room, needing to change into our trunks, and I was about to leave the room in order to let him change first, when to my surprise, he strips off in front of me before I could go. We had never seen each other naked before, and I managed to sneak a quick peek. He was soft at the time, though his balls hung really low.
"What are you doing?" I asked, taken aback.
"What?" he replied. "I thought we could both just get changed in here."
With that, I quickly discarded my clothes, standing naked in front of him. My penis was erect, and I started helping him look for his swimming trunks while deliberately letting him get a good look. At this point, we were both stark naked, and he quickly started to get hard as well.
"Are you happy to see me?" I teased nonchalantly, as he started to go a bit red. "That's okay, it happens to everybody." He then relaxed a bit.
"Gah, I can't find my trunks! I swear I packed them." He said.
"Hey, we're all guys here. Why don't we just go in like this?"
He seemed to consider it for a split second, but he then agreed. We made our way to the bathroom and got into the already-filled jacuzzi. My parents had gone to bed by now, so there was nothing to worry about. We sat around for a couple of minutes, unable to keep our eyes off one another's boyhood. I thought this could lead to something, so I tried to break the ice:
"Try holding your penis up to the jet. It feels amazing!" I said, leading by example. Jeremy followed suit.
"This is alright," he said.
"Alright? Try pulling your foreskin back, since you're uncircumcised."
"Much better," he stammered as a look of sheer ecstasy crossed his face. "So how come you're circumcised?"
"I got cut a few years ago by choice. I have a Jewish friend, and his is so much cleaner and better looking."
"Ah, I see. So, you have seen it?"
"Yes, our parents are great friends, and we used to play doctor when we were kids. Nothing ever happened though, we were too young. Mind you, I would have loved to try...".
"Do you want to try with me?" he asked.
"Hell yes!" With that, we both started stroking our penises in front of each other. After a couple of minutes, I stopped him. "I want to try something, if it's okay with you." I said, gesturing that I want to touch his penis. He removed his hands, and I slowly pushed him on his back in the hot tub. I then mounted him and skinned his penis, touching my bare head to his. Slowly, I rolled his foreskin forwards as it encased both our penises, and I started tossing us both off. After just a few more minutes, he had reached his limit and he started to cum, his juice mixing with my penis. This sent me over the edge, as I also ejaculated in his foreskin. I dismounted him, and Jeremy and I sat in the hot tub for a few more minutes before getting out. We ended up sleeping naked, and we began to have regular wank sessions. It is without a doubt that this strengthened our friendship, and to this day, we still masturbate together. He has also gotten circumcised since then when he was 16, as he absolutely adored my cock, and although we can't use his foreskin anymore, we still have lots of fun.