Joke--Shamelessly Stolen

"A person who cannot tell a doughnut from a coffee mug."

I wonder if anyone has ever prepared a mobius-doughnut.

I've heard that one too many times to be funny.

Try this one: Some researchers are investigating how different people think. They call in people from different fields and ask them, "You are sitting in your living room when the curtains catch fire. In the hall is a bucket full of water. What do you do?"

Naturally, everyone answers, "I run to the hall, take the bucket of water, run back into the room, and throw the water on the curtain."

The follow-up question is more interesting: "You are in the living room and the curtain catches fire. There is an empty bucket in the hall. What do you do?"

Only the mathematicians give an unexpected answer. They reply: "I run to the hall, take the bucket to the bathroom, run back to the room, put the bucket down in the hall, run into the room, and sit down."

Oops. I forgot that the mathematicians fill the bucket with water while they're in the bathroom.

Bummer. Messes the joke up pretty badly :-(