Finding your site has helped me broaden my horizons; I am glad to have a place to share this story
This took place around 1988 when my son was 16. I am a Vietnam Vet. I kept my uniform in a basement closet all those years and still have it today, though I outgrew it about 1974. Anyway, my son had this friend at the time who I was sure was gay. It was OK with me, but I did wonder if they were doing anything. So I had the usual sex talks with him but I emphasized teaching him safe sex techniques. I even showed him (on myself) how to apply a condom and had him put one on himself. So we were more open than most fathers and sons I think, but he never spoke about his sex life or lack of one.
Then one Saturday I left to take the car for an overhaul while his mom was shopping. He was home alone with his buddy. A few blocks from home the car stalled out. I walked back in a downpour to call road service. I came in and went right to the basement to strip because I was soaked. I walked right in on this scene. My boy was dressed up in my old military uniform with his dick and balls hanging out the fly and kneeling under him was his buddy completely naked. My boy was jerking off into this guy's face! I don't know if my timing was just perfect or if it was the effect of his looking up and seeing me there, but exactly then he started throwing his load right into his buddy's face.
I stood there like a jackass for many seconds as the boys scrambled around in a panic not knowing what to do. I did finally 'take command' though, and told them to calm down and get dressed. They did that, which gave me time to compose myself. I sat them down and told them I thought jerking off together was no big deal. That calmed them a bit more and I told them that what I saw would always stay our secret. I could see that was about all the stress any of us could take so I dried off quickly and went upstairs to call road service. I had further talks later with my boy to try to figure out what his relationship was with his friend involved, but all he would do is tell me firmly that he would not do anything like this ever again-even though I made it clear I didn't object to him jerking off with a buddy, and I never asked him to stop it.
A few years ago he brought up the old incident himself to tell me how mortified he was about me seeing them, and I told him how insignificant I thought it was, and if it weren't for the anguish it caused him, how funny it would be-and then we were both able to laugh over it. So I think it is resolved for him now.