What do you get when you cross a grape with an elephant?
  Grape Elephant sine Theta.

What do you get when you cross a mosquito with a mountain climber?
  Trick question -- you can't cross a vector with a scalar.

What's yellow and equivalent to the axiom of choice?
  Zorn's Lemon.

What's purple and commutes?
  An Abelian grape.

(What if it's worshipped by a limited number of people?
   A finitely venerated Abelian grape.)

How many mathematicians does it take to screw in a light bulb?
  One, who gives it to six Californians, thereby reducing it to a previous joke.


(How many zen buddhists does it take to screw in a light bulb?
  Two -- one to screw it in, one not to screw it in.)

(How many militant feminists does it take to screw in a light bulb?
  "That's not funny!")