With the crunch that is the end of any semester fast approaching (wait, it’s here!), I figure it’s time for a dose of math humor. Yes, mathematicians have just as good a sense of humor as anyone else. For example:

- A physicist, a biologist, and a mathematician are sitting on a street corner observing a vacant house across the street. They see two people enter, then a short while later, three people leave. The physicist says, “There was an error in the measurement.” The biologist says, “They must have reproduced.” The mathematician says, “Now if one more person enters the house, it will be empty!”
- What’s purple and commutes?
*An abelian grape*.

See? (OK, maybe the humor’s a little specialized, but it’s still, you know… funny.)

MathWorld has a humor index, and Wikipedia has an entry on the mathematical joke. A Google search for “math joke” turns up **2.1 million** hits.

What I want to know is: What’s your favorite math joke? Leave a comment (or two or three or…) and give us all a good laugh.

[Note: Puns and other “bad” jokes are strongly **encouraged**, as long as there’s a hint of math in them.]