Careful you fool!
Some people have said different things about which was the best joke. For me it was this one.
Clouseau [After aiming with a gun at another police officer (without realizing it on the heat of a conversation), the other officer gently tries to push Clouseau's hand away in order to make Clouseau stop aiming at him]:
"Careful you fool! You realize this gun is loaded?" [and leaves immediately in a hurry]
I can't stop laughing with this. I really can't.