Q: What is non-orientable and lives in the ocean?
A: Möbius Dick...
A mathematician organizes a raffle in which the prize is an infinite amount of money paid over an infinite amount of time. Of course, with the promise of such a prize, his tickets sell like hot cake.
When the winning ticket is drawn, and the jubilant winner comes to claim his prize, the mathematician explains the mode of payment: "1 dollar now, 1/2 dollar next week, 1/3 dollar the week after that..."
"The number you have dialed is imaginary. Please, rotate your phone by 90 degrees and try again..."
From a former prof. - http://www.math.ualberta.ca/~runde/jokes.html