Answer:
What is the building that you leave without ever having entered.
What goes up the hill and down the hill, And spite of all, yet stand still?
Three doctors said that Bill was their brother. Bill said he had no brothers. Who was lying?
In 1990, a person is 15 years old. In 1995 that same person is 10 years old. How is this possible?
4 rubber ducks were floating in the bathtub, 2 floated away and 2 drowned. How many ducks are still alive?
What did the piece of wood say when he saw the screwdriver and screws approaching?