Answer:
What is as big as you are and yet does not weigh anything?
How do you drop an egg and never break it?
How is it possible to always find what your looking for in the last place you look?
What can you hold in your right hand but never in your left hand?
An archaeologist unearths a coin bearing the inscription "57BC". How does he instantly know that it's a forgery?
A red house is made out of red bricks. A blue house is made out of blue bricks. What is a green house made out of?