I know bists and guitarists use tabs, but what do DRUMMERS use to write down music...?

Their own set of tabs. Each line signifies a different piece of the kit. Sometimes there will be a letter in front of each line like S for Snare C for Cymbals, etc. For cymbals a circle can symbolize it to be open and an X for it to be closed. It can vary from musician to musician, but there's a sort of standard. Usually the musician will have a key or legend to explain their tabs.