Here's an oddball for you:
My sink has one of those metal baskets in the drain that drops down when you turn it 90 degrees to stopper up the drain so you can fill the sink with water. Normally it sits up a little so it lets the water out while catching the food particles.
I can't keep the danged thing up! The swirling water going down the drain spins the basket and causes it to drop in and stopper the drain.