How come there is no Knock-Knock joke about America?

How can you tell if you are allergic to pollen?

How can you get four suits for a dollar?

What runs from one city to another but never moves?

How do you fix a broken tomato?

What do Astronauts eat from?

What is the most musical part of the chicken?

Why aren’t dogs good dancers?

How does a beaver open her computer?

How do two geese end a fight?