This one I heard from a friend.

A bank robber is at the head of the line in a bank. He pulls out a gun and demands money from the teller. She gives it to him and he turns around and looks at the guy behind him in line. “Did you see that?” he asks. The guy says “Well, yes I did. You just robbed the bank.” So the robber shoots him.

Then he notices the couple who had been standing behind the dead guy. “Did you see that?” he asks the man. “No,” the man says, “but my wife did.”