One day my friend Preston called me and asked me to spend the night at his house. He was 13 and I was 12 at the time. It was a fairly normal sleep over until it was time to go to bed. We slept in the basement. That way we could stay up all night and make as much noise as we wanted to, without his parents getting mad.
We soon changed into our PJs which were nothing more than our underwear and t-shirts. When he asked me what I wanted to do, I suggested that we play doctor, because I just had a doctor's appointment that day. He said sure. He examined me first. First he checked out my nose, ears, chest, etc. Then without any further notice, he pulled my underwear right off me and left my penis in the open. I was shocked at first, but I played along. When he started to feel it, it felt really good.
Then it was my turn to be the doctor. I also checked out his mouth, chest, etc, but did so quickly. I was so anxious to see something I had never seen before in my life, another boy's penis.
I pulled his underwear off and looked at it. It looked strange to me. It didn't look like mine. He had very little hair (I had none), but I was still amazed by this. What caught my eye the most was the tip of his penis. He explained to me that I was circumcised and he was not. He pulled his foreskin back to show me that they did in fact look the same. After we finished playing doctor, we kept our undies off and played with each other for a while.
We actually fell asleep naked in the bed together (it was a fold out couch), but woke up before anyone else did and quickly put on our pants. We have had a few more experiences since, but I will never forget the first time I ever saw another guy.