http://www.math.ualberta.ca/~runde/jokes.html Some of these are pretty funny -Herr-

A carpool is a group of people who commute with each other. Therefore, a carpool is an Abelian group. -Kyle-

What do you call someone who's afraid of abstract albegra?

Homomorphicphobic

An infinite crowd of mathematicians enters a bar.
The first one orders a pint, the second one a half pint, the third one a quarter pint...
"I understand", says the bartender - and pours two pints.

Q: Why do mathematicians, after a dinner at a Chinese restaurant, always insist on taking the leftovers home?

A: Because they know the Chinese remainder theorem!

Q: What does a mathematician present to his fiancée when he wants to propose?

A: A polynomial ring!