Answer:
How do you discover something that does not exist?
Twelve pears hanging high, twelve men passing by. Each took a pear and left eleven hanging there. How can this be?
What is the building that you leave without ever having entered.
A man is twenty years old but has only had five birthdays. How is that possible?
How do you drop an egg and never break it?
If a rooster lays an egg on the exact peak of a barn, which side does it fall?