My cat has this habit of "washing his hands" by banging them on whatever's nearby after every use of the litter box. The other night, he noisily banged against a box.

Voice from the bedroom:

Aidan: What's that?
Me: Crookshanks is washing his hands.
Aidan: Why?
Me: Because he just pooped.
Aidan: He scared me!
Me: He's sorry.
Aidan: Okay.