Upside Down Seating Arrangement

How do you get four prostitutes on one chair?

You turn it upside down.

Explanation

This is a classic riddle-style joke that plays on the listener's expectation of a complex or suggestive answer. Instead, the solution is a simple, literal one involving the physical manipulation of the chair, making the 'four prostitutes' fit by changing the chair's orientation. This misdirection is the core of the humor.