A man walks into a bar and asks for a glass of water. The waiter pulls out a gun from under the bar and points it at the man's head. Then the man says "thank you" to the waiter and leaves the bar.
The man entered the bar to get rid of his hiccups by drinking a glass of water. The waiter - who noticed this - took out his gun and pointed it at him to cure them by frightening him. The man - now cured - thanked the waiter and left the bar.