Two. One to change it and another one to change it back again.
A what?
5 1 to hold the bulb and 4 to spin the ladder.
Six. Why? It just does! OKAY!
Unlike milk it doesn't have to change color. Why does Budweiser go faster through you than beer? Unlike beer it doesn't have to change taste.
When their lips move
Both should be changed regularly, and both for the same reason.