Answer:
What is the building that you leave without ever having entered.
A traveller moved from North to East then to West and lastly South.. What was he looking for?
How many bananas can you eat if your stomach is empty?
Six glasses are in a row. The first three are filled with milk and the last three are empty. By moving only one glass, can you arrange them so that the full and the empty glasses alternate?
Twelve pears hanging high, twelve men passing by. Each took a pear and left eleven hanging there. How can this be?
Almost everyone needs it, asks for it, gives it. But almost nobody takes it.