Light Bulb - Burger King

Q: How many people in a Burger King advert does it take to change a lightbulb?
A: None. "I can't change my lightbulb. But I can change my burger to a Burger King burger."

Light Bulb - Grad Students

Q: How many graduate students does it take to screw in a light bulb?
A: Only one, but it may take upwards of five years for him to get it done.

Racists to Screw in Lightbulb

Q: How many racists does it take to screw in a lightbulb?
A: None -- they don't want to be enlightened!