In college, my GF shared a dorm room with two other girls. GF had the bottom bunk, one roommate had the top and a 2nd roommate had a single bed on the other side of the room. Of course, this didn’t stop either of us from middle of the night adventures. One night GF was between my legs administering me orally when roommate in the single bed wakes up. GF was too preoccupied to notice; I looked over and could see roommate laying on her side facing us, eyes open. Then she sat up and leaned back against the headboard. She watched silently for 10 minutes or so until GF’s talents got the better of me and the two of us fell asleep. Nothing was ever said about it; I’m pretty sure rommate didn’t mention it to GF.
One other time a bunch of friends shared a beach house and I shared a room with a buddy. I met a girl at a bar and we went back to the house later than everyone else, so by the time we got to my room my roommate was already asleep in his bed. I think the girl took this as a challenge and we went through a number of rather acrobatic positions that night. Despite our efforts, my roommate snored through the whole thing. When I told him about it the next day he was pretty disappointed he didn’t wake up.
On half a dozen occasions, maybe more, one or both of the kids walked in on me and my wife during a morning session, right at the point of no return for one or both of us. They’re still too young to know what’s going on, though, and usually enter talking and chattering, so it gives us enough time to quickly regain our composure and act like nothing is going on. We always make sure that the morning sessions are done discretely under the covers, just in case, so we’re not hanging from the ceiling trapeze, or anything.