When I was traveling a few years back, red eye flight overseas, a woman goes into the bathroom and 30 seconds later is followed by some dude. Ok, not too surprising. They come out, go back to their seats and a half hour later she goes to the bathroom and 30 seconds a different dude followed her in. About an hour later happened again with a third guy. After that the the woman goes to return to her seat and the stewardess had to tell her the restrooms have a capacity for one. Every guy in the cabin was paying attention by then.