Good Riddles

Question: A man goes into a barbershop and gets a $15 haircut. He pays the barber with a $20 bill, but the barber doesn't have change because it is an especially slow day. The barber goes to the flower shop next to his own and trades the $20 bill for a $10 dollar bill and two $5 bills. Then he gives the man his $5 in change.

Later the lady from the flower shop confronts the barber and tells him that the $20 bill he gave her was counterfeit. The barber agrees and he gives the lady a different $20 bill.

Later that day he tries to figure out how much money he lost. What did he lose?

Question: What do you call 2 Us?

Question: A man hangs his hat and walks 500 yards with his eyes closed. He then turns around and shoots his hat with his pistol with his eyes still shut.

How did he do this?

Question: You're in a room with no doors or windows. Just a mirror and a table.

How do you get out?

Question: Had by few but treasured by all,
I'm on the inside and outside and I make men fall.

What am I?