Walked in on me doing:
Most recent was this past Friday, the gf and I were in Myrtle Beach on vacation sharing a room with two other couples. The one that had the other queen bed was out of the room at the beach. The second couple was in on the pullout sofa bed (it had two different rooms). Well she was going down on me, in her panties and tank top while I was naked. The guy from the other couple just opened the door (because you have to go through the bedroom to go outside the room) from the sofa bed and just walked in. He said "oh dude I'm so sorry" about 10 times in 30 seconds, rushed out, then she got back to going down on me lol.
Parents (both mom and dad) walked in on my whacking off in HS. Also had mom walk in when I had Kazaa up downloading all this porn, and start going through stuff on my desk. I was on the other side of the room, jumped over my bed (had a queen that was about 4.5 ft off the ground), and minimized it as fast as I could lol. Another time gf was giving me a bj and friend came over (that I asked to but forgot I asked him to). That was a bit awkward lol.
I walked in on my gf at the time and best friend at the time going at it humping and having dry sex while hands were down each others pants.