Earlier tonight, while the girls were getting ready for bed:
Shylee: Why do we have to brush our teeth every day?
Me: Because the Sugar Bugs poop in your teeth and if you don't brush them clean, the poop rots your teeth and makes you have stinky breath.
Shylee: Oh... I don't want ANY poop in my mouth. (Brushes faster.)
Morgan: Yay! Poop!