Best short medium riddles for teens

What gets shorter when you close your arm?

An iron horse with a flaxen tail. The faster the horse runs, the shorter his tail becomes. What is it?

What can you lose that will cause other people to lose theirs too?

I'm in your phone. Sometimes I laugh. Sometimes I cry. I even flip you off from time to time. What am I ?

There are different types of stones available. However, there is one type of stone you cannot find in the ocean! What is that?

What type of cheese is made backwards?

Find three positive whole numbers that have the same answer added together or when multiplied together.

What did the boy bird say to the girl bird on Valentine's Day?

What do you throw out when you want to use it, but take in when you don't want to use it?

You see a boat filled with people. It has not sunk, but when you look again you don't see a single person on the boat. Why?