"Papa, do you want to hear a joke?"I'm fairly certain she's never actually heard a cop-doughnut joke. Of course, like many children, she's interested in policemen, and the subject of doughnuts comes up often enough (Doughnut Fridays is pretty much the only part of my job she understands). But the random combination of the two?
"What if a police officer went to a doughnut store and bought two doughnuts?"
"That's pretty funny."*
This can only be explained by the collective unconscious.
* Ok, so it wasn't actually funny in a straightforward jokey-joke way, but it was still funny. More of a meta-joke.