Fun Riddles

Question: A man is doing some work on his home and goes to a hardware store. He goes up to the clerk and tells him what he wants. The clerk tells him that each one is $1. He tells the clerk he would like 5000 and he is charged only $4.

What did he buy?

Question: What starts with "P" and ends with "E" and has more than 1000 letters?

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

How do you get out?

Question: I am a big threat to humanity,
but you wouldn't get rid of me even if you could.

What am I?

Question: Light hides me and darkness kills me.

What am I?