Answer:
If you count 20 houses on your right going to the store and 20 houses on your left coming home, how many houses did you count?
When you put this in a heavy wooden box the box will become lighter
How do you discover something that does not exist?
Mr. Smith has two children. If the older child is a boy, what are the odds that the other child is also a boy?
There are two sisters: one gives birth to the other and she, in turn, gives birth to the first. Who are the two sisters?
What is full of holes but still holds water?