When your best friend is clearly having a good time in the bedroom next door, and the walls between is thinner than a plank of wood, then it's awkward.
For some reason this reminded me of a story my friend told me just a few weeks ago when he was back in town from college:
(Short-Short version)
After hanging out with a guy friend and some chick that happened to be a security gaurd for his campus that they just met that evening and getting super wasted...
They go back to her house to watch movies, somehow ended up in bed with the chick in the middle. He had his back to them and felt her hands running up and down him, peeked over and she was doing the same to him so after a bit they both have the same idea and start feeling her up some. He claims all he grabbed was boob (i bet it was less cuz he's a loser).
I forget how but he stopped fooling around cuz "it was weird" so he turns his back to them again and hears them fooling around. Says it took him 10 mins to realize they were screwing RIGHT NEXT TO HIM in her bed. He leaves, goes to the couch in the living room to sleep.
They come out and start screwing around in the other couch, he leaves again and goes back to the room.
Freaking idiot.