Wuh-wuh-wuh-one.
One, but you can be sure a whole Reddit community will appear to expand the joke, make it funnier and eventually run it into the ground.
A. Nobody knows, there's no light.
Let's go fishing
Both should be changed regularly, and both for the same reason.
100. 1 to actually clean the shower, and 99 to stand around and talk about how filthy it is.