Frog Man

"Mama," my nine-year-old son said.  "Did you know we're closely related to amphibians?"

I looked at that boy funny.  "What do you mean, Bubba?  Amphibians are cold-blooded animals, and humans are warm-blooded."

"Humans and frogs can both hang out in water and on land."

"But what about the warm-blooded, cold-blooded thing?" I asked.

He thought about that a second.  "Well, frogs are cold-blooded and they croak.  When humans become cold-blooded, they croak."

Brilliant!