Did you hear about the most unusual Christmas present?

Every Christmas a man bought his wife a very unusual present. Last year he walked into the house and put a very tiny tree in the middle of the room. It had no needles on it. The only thing on the tree was a bullet tied to a branch. The wife walked around the tree and finally said, "O K I give up. What is it?".

He smiled and started to sing,"It's a cartridge in a bare tree". (It helps if you sing the last line)