Yeah I walked in on my brother once, it was very embarrassing for both of us and awkward too. I wish it never happened..... :toilet:
My brother. My parents were on vacation and we were both in our early 20's. In the middle of the night our fire alarm went off, it was only due for batteries but it went off full force. I barged into my brother's room to get him and he had was nude with a huge erection and very much awake. He said something along the lines that I had 'caught' him but with all the commotion didn't seem all that embarrassed. I have to admit I couldn't help notice his huge erect penis but tried to not embarrass him, threw him something to cover up and said 'Never mind that, the house might be on fire!' And we scurried out. Turns out it only needed batteries but better safe than sorry! We never spoke of it again but I have to admit I'll never forget that sight, since it's (unfortunately!) the biggest one I've ever seen.
On occasions my father had to share my room when I would be about 12/13. I heard but did not see him masturbating. This was many years ago when toilets were outside the house so I did see the results in the pot.
I seen my father growing up sometimes when I walked in which must be a common thread since my sons have walked in on me on occasion. Possibly payback for walkin in on them. Nothing is ever said. Pretty casual about it.
Had a friend that was masturbating inside his sleeping bag on a camping trip when we were kids. I acted like I didn't know and he was being very casual about doing it.