Panda

A panda walks into a bar, sits down and orders a sandwich. He eats the sandwich, pulls out a gun and shoots the waiter dead. As the panda stands up to go, the bartender shouts, "Hey! Where are you going? You just shot my waiter and you didn’t pay for your sandwich!" The panda yells back at the bartender, "Hey, I’m a PANDA! Look it up!"

The bartender opens his dictionary and sees the following definition for panda: "A tree dwelling marsupial of Asian origin, characterized by distinct black and white coloring. Eats shoots and leaves.