I am a 15 year old girl and am an only child. My parents are friends with a couple who have a boy my age and is also an only child. I have never seen a man masturbate or even seen a penis for that matter.
One time in the summer my parents and their friends decided to go to a nude beach. They figured that I was at the right age that it would be ok for me to see people naked. The other couple brought their 15 year old son 'Tom' with them too. We got there and put our clothes in a locker and my parents and their friends said that they were going swimming in the lake. There was a sauna there and 'Tom' said he was going in. I went in too. We were the only two there.
His penis was still soft and I said that I never seen a naked boy before. He said he had never seen a naked girl. We were touching each other and I asked 'Tom' can I touch your penis? He said as long as I can touch your vagina. I said sure, so I touched his penis and he touched my vagina. Then with my free hand I reached behind him and grabbed his arse. With his free hand he touched my tits. Then he said lets take a shower.
We were in the shower and we did the same thing as before. Then he said give me a hand job. So I did. Then he stuck his fingers in my wet pussy.