Yes, I have caught my sister (thousands of times as we shared a bedroom in our parents house or an apartment later), my cousin (we lived in the same apartment for years) both our kids and my wife!!
With my cousin, we lived in the same building (different apartments) for years, not the same apartment.
I caught a neighbor in college, I got to my dorm and opened up the window because I was out all weekend and it was hot and stuffy. I looked down and across the hall and a girl was lying on the floor one hand buried in her vagina and the other had was up her shirt I presume playing with her breast. She looked up and saw me in the window with my light now on. She rolled over and then dashed out of sight. Next moment the light went out in her room.
Walked in on my stepson once when he was just at the point of no return. Before either of us could react, he shot a load all over himself.
I went to my aunt’s house for the summer a few times. She has two sons close to my age. I was laying out by the pool in my bikini. My cousins came home from a basketball game from down the street. They went and changed and jumped in the pool. They splashed me and we had fun in the pool playing volleyball or whatever the pool form is. lol A few times I felt one or the other accidentally touch me. But didn’t think much of it. I got out and laid in the sun to dry off and the boys went upstairs. About an hour later I went up to take a shower and hear someone in the room I was using. I peeked in and one of them was using my thong to jack off and sniffing them. I couldn’t believe it. I turned around and went into the shower. I kept thinking about how big he was and what he was doing. I ended up playing in the shower for a while with that image in my head.
I don't know if I "caught" a guy masturbating, because he may have wanted to be seen. I was staying in a hotel in New York City. My window overlooked a smallish air shaft, maybe 15 feet across, with other similar rooms on the other side of the shaft. One night, I went to my window, and across and one floor down, there was a guy laying naked on the bed with all his room lights on, jacking his lubed up hard cock. I watched him a few minutes until he ejaculated on his belly and chest. After a few more minutes, he wiped himself with a towel he had on the bed, got up and went to his bathroom. He never looked to see if anyone was watching. I got hard watching, and closed my curtains, stripped all my clothes off, and jacked off myself, remembering watching him.
I wasn't aware of it at the time but my ex sister in-law admitted to me she watched me stroke myself off to completion to then masturbate herself to what she had witnessed. I was lying on the lounger on the deck enjoying the sun rays when I removed my bathing suit and started jerking off unknowing she was watching through the kitchen window. She had a key to the house and was just dropping things of for her sister when she saw me through the kitchen window. She said she watched me shoot my load all over my stomach and chest to rush home and get herself off to the images of my cock shooting a load.
Actually yes, when I was young I caught my older brother masturbating in my sisters room playing with her underwear. I had a friend in middle school that I would watch Cinemax/skinemax when he spent the night on weekends. We would also masturbate together. A few times we jerked each other off, and would have multiple orgasms staying hard from one to the next. Usually just two in a row, but sometimes more. I also caught a roommate masturbating once in college. And my ex-wife a few times in the moring.
I once walked in on my mom going to town on herself. Quite traumatizing, actually. My high school best friend and I masturbated in the same room as each other, to a picture of a girl we knew, and swore it wasn't gay. Even though we totally enjoyed it but weren't ready to admit to it yet I walked in on a friend jerking it once. Didn't see anything, but lowkey wish I did. I walk in on my fiance touching herself from time to time. Sometimes I join in and fuck her, and other times I just watch her while touching myself because it turns me on.
I’ve never honestly walked in on anyone masterbating but if I ever do I hope it’s a female lol and not a relative
Saw my mom once when I was a teen, she did not know. Caught my wife a few times with her big vibrating dildo
All in the family one can't help but see each other naked at one time or another. no big deal............