In college, a friend of mine called and asked if I wanted to supper with he and his girlfriend. I said sure, and he said to "come over" in a few minutes. So, I did.
Usually, whenever we visited, we would simply open the others' door. If it was locked, we were "busy". His was unlocked, so I opened it. The room was dark - but the hallway threw in enough light that I could see he in his underwear hovering over his girlfriend, dressed in her panties and bra.
I acted like I saw nothing when he yelled "Greg! Close the door!", and closed the door.
My first college roommate was notorious for having sex with his girlfriend any time she was over. Even when I had my schedule posted (I told him to pay attention to it so I would stop walking in on them), I would find he and his girlfriend going at it. To say the least, they were not an attractive couple. In fact, they were both quite ugly.
It finally ended when I decided one day, enough was enough, and that I was staying. And leaving the door open.
"Uh...Greg. Could you close the door."
"Nope."
Awkward (for him) pause.
"But, I don't have anything one under here. Kelly's naked, too."
"Tough shit."
He got up and closed the door.
I went out to fill a pot with water so I could make some Ramen Noodles. I left the door open when I left.
When I came back, the door was closed. I opened it, and left it open.
He closed it.
When the noodles were done boiling, I again left...leaving the door open. When I came back, it was closed.
I left it open.
He again closed the door. By now, his girlfriend was fully dressed (fortunately, I never saw anything). He dressed, and they both left in a huff.
A few weeks later, I was in the room next door, watching some movies with some other guys and gals in the hall. Lance came knocking at the door, dressed in a robe.
"Greg, your girlfriend's on the phone."
"Cool." I got up and headed towards our room.
"She interrupted me and Kelly."
"That's a real shame."
"She called three times. First couple of times, I told her to call back. She called back a couple of seconds."
"That's a real shame." I picked up the phone. "Hey, Jen, what's up?"
"Greg...were Lance and his girlfriend having sex?"
"Yep."
"Did I interrupted them?"
"Yep."
"Three times?"
"Yep. You did good."
"Cool! See you later tonight!"
"See you!"
Lance was a real dick.