What is the funniest joke you have ever heard?

Hey everyone
Tell as what is the funniest joke you have ever heard?

Here is a good one:

A tandem rider is stopped by a police car.

"What've I done, officer?" asks the rider.

"Perhaps you didn't notice, sir, but your wife fell off your bike half a mile back . . ."

"Oh, thank God for that," says the rider - "I thought I'd gone deaf!"