Well, a coin.
A truck driver is going down a one way street the wrong way, and passes at least ten cops. Why is he not caught?
How can you drop a raw egg onto a concrete floor without cracking it?
If there are 6 apples and you take away 4, how many do you have?
Some months have 31 days, others have 30 days. How many have 28 days?
What goes up and down, but still remains in the same place?
What gets wetter and wetter the more it dries?
How can you lift an Elephant with just one hand?
What is the sound of one hand clapping?