My first time jacking off with another guy was when I was 12 and he was 16. He was my brother's bud. We went swimming in a nearby lake.
After we were about 100 yards from shore we stood up and we both had hardons. We dropped our swim trunks and showed our cocks to each other. Mine was 5 inches and his was a good 7 inches.
We felt up each other and jacked off each other. It was amazing watching our cum shoot like jets in the water. We were jack off buds for 2 years until he got married at 18. But we still jacked off each other once or twice a week anyway.