Clogging the loos...
I saw this once on a TG flight from LHR to BKK in economy... It was a night flight, everyone had been fed and watered and was sound asleep. I got up to use the loo, went to one of the lavatory areas and someone's grandmother was spread out in the middle of the space fast asleep. You couldn't use about half of the toilets because she was up against the doors and you couldn't open them. As it was the middle of the night there wasn't a queue or anything for the toilets. I just stepped over her and found an empty cubicle that she wasn't blocking...
Definitely one of my more bizarre flying experiences!