when you can hear people having sex REALLY LOUDLY in the bedroom next to the living room, which is where you are using an ethernet connection because your computer just isn't doing wireless anymore. Plus the living room door is shut tight and they would definitely hear you going upstairs, which is where you need to go because it's time for sleep and you're only downstairs because of work.

Mid-orgasm - probably same as walking in
Straight after - makes you look like a pervert
Ten minutes after - probably still a pervert

Oh god. I'll never be able to go upstairs.