The ability of the human butt to know when it is close to its home toilet.
I didn't have to go during the whole five hour drive, but as soon as I turned onto my street my GP-ASS kicked in and I almost soiled my shorts.
Turning on the bathroom sink with no intention of actually washing your hands.
I was just in the bathroom and overheard my boss pretending to wash his hands; but it was an obvious ghost rinse.
Remaining motionless and silent in a toilet stall while waiting for everyone else to exit the bathroom.
Bathroom traffic was unusually heavy this afternoon and my leg fell asleep while I was playing poopsum.