Ok, i cracked up on a few. Heres a few oldies, but goodies:
What do you a call a cow with no legs, Ground Beef
What do you get when you cross a rhino and an elephant, Elephino
What did the Austrian guy say when his cat ate his bird, Kitty Kitty Bang Bang
What is black, white, and red all over, a newspaper, or a sunburned zebra
Those are the only ones I remember right now lol