Light Bulb - Falling

Q: Why did the light bulb fall out of the tree?
A: Because it was doing an impersonation of the sun, setting.

Light Bulb - Mutant

Q: How many mutants does it take to screw in a light bulb?
A: Two thirds.

Light Bulb - Waiter

Q: How many waiters does it take to change a light bulb?
A: None, even a burned out bulb can't catch a waiter's eye.