What do you call a lazy kangaroo?

A pouch potato.

Old mathematicians never die...

They just lose some of their functions.

When a neighbor's home was burglarized, I decided to be more safety conscious. But my measly front-door lock wasn’t going to stop anyone, so I hung this sign outside: "Nancy, don’t come in. The snake is loose. Mom."

How do you put a baby alien to bed?

You rocket to sleep.