When I was 13 years old, me and my cousin (who was a only a couple of months younger than me) used to spend a lot of time together. I was tall and well-built for my age with black hair and brown eyes, and he was short and skinny with light brown hair and blue eyes.
One day, he had come over to my house and we both got bored after a while. While we were trying to think of something fun to do, he suggested that we show each other our penises. I was opposed to it at first, but then I could feel my little dick getting stiff and I reconsidered.
We happened to be alone at the time, but we both went up to my room and locked the door for good measure. We both stripped down to our boxers, then we agreed to both pull down our underwear on the count of 3. We discarded of our last piece of clothing and just stood there, staring at each others' naked bodies. We were both fully erect and I noticed that he had no pubic hair, while I had a few black hairs sprouting from the shaft of my cock. We were both uncircumsised.
After a bit of staring, I suggested that we compare sizes and he agreed. He then laid down on my bed, his hard penis flopping onto his stomach. I leaned over him and pressed mine against it and found mine to be longer and fatter. I then grabbed a ruler from my drawer and measured my penis, then measured his. It turned out that I was 5 inches long and he was only 4 inches.
I was extremely horny by now. I had learned to masturbate long before that, and I asked my cousin if he had ever done it. He didn't know what it was, so I offered to show him. I laid down next to him and grabbed his penis. As I started to masturbate him, he let out a few soft moans of pleasure. After about two minutes, he told me to stop because he had to pee. I started stroking more vigorously, giving him his first dry orgasm.
My cousin then wanted to return the favour, so I showed him what to do and he started stroking me with much enthusiasm. I was extremely horny and I reached climax very quickly, a drop of cum oozing out of my penis. This intrigued my cousin, and I explained to him what it was and that he should start producing it soon. He then wiped it up with his finger and slowly inserted it into his mouth. He seemed to love the taste because he eagerly mopped up the rest and ate it all. I then heard the garage door opening, so we quickly got dressed and went downstairs innocently.
This happened every time he came over after that, and it got even more fun when he started producing semen a few months later. However, that is another story for another time.