This story happened to me and my 16 year old son. We were up at our cabin in the middle of the woods. It was just the two of us for two weeks. The second day we were there we decided to go swimming in the lake that we own. It is only a small lake and all the land around it is ours and is covered with trees. You can't see the lake unless you come on our land. We started to look for our swimming trunks but we couldn't find them. So I said let's go naked. No one will see us and we had seen each other naked before. He agreed. We took off our clothes and left them in the cabin and walked to the lake nude. It was close to the house. We were swimming and playing around for a while.
Then my son got out of the water and lay on a rock to get some sun on his very thin but muscular young body. I did the same. I couldn't help seeing his good looking cock. Then out of nowhere he got a huge erection. Then he said he hadn't masturbated in three days and asked if he could pleasure himself. I said sure as long as I could to. So we both started. Before long I could hear him starting to breathe heavier and he came all over himself. Then I closed my eyes trying to think of somthing sexy then I felt something and opened my eyes. My son was straddling my legs. He grabbed my cock and said it looks like you need some help. Then I grabbed his huge cock and helped him as well. We did this a few more times at the cabin and agreed if we felt like doing this at home we would.