Doctor : Let me tell you a story: "There was once a Hunter who always carried a gun wherever he went. One day he forgot to load bullets when he went out. A Lion suddenly jumped in front of him. In order to scare the Lion, the Hunter pointed the gun at him, and shot the Lion, and it fell dead!
Guy : Nonsense! Someone else must have shot the Lion..
Doctor : Good! You understood the story. Next patient please..