Good Riddles

Question: A cowboy rode to an inn on Friday. He stayed two nights and left on Friday. How could that be?

Question: When it is alive we sing, when it is dead we clap our hands. What is it?

Question: I am an instrument that you can hear, but you can not touch or see me.

What am I?

Question: When do you go at red, but stop at green?

Question: The more you add, the less it weighs.