Answer:
How do you discover something that does not exist?
What is as big as you are and yet does not weigh anything?
What goes up the hill and down the hill, And spite of all, yet stand still?
Mr. Smith has two children. If the older child is a boy, what are the odds that the other child is also a boy?
If you have 30 white socks, 22 black socks, and 14 blue socks scattered across the floor in the dark, how many would you have to grab to get a matching pair?
What do you purposefully put lots of in and on your body, but run away from when you encounter it outside?