A: Because people keep hitting them with dictionaries.
Q: Why can't blondes put in light bulbs?
A: They keep breaking them with the hammers.
Q: What is a cool refreshing drink for a blonde?
A: Perri-air.
Q: Did you hear about the blonde coyote?
A: Got stuck in a trap, chewed off three legs and was still stuck.
Q: When is it legal to shoot a blonde in the head?
A: When you have a tire pump to reinflate it!
Q: Did you here about the blonde who shot an arrow into the air?
A: She missed.
Q: What is it called when a blonde blows in another blond's ear?
A: Data transfer.