A thug walks menacingly into a bar, wearing a slouch hat and a trench coat, carrying a trombone case. Everyone moves away, and some head for the door as quietly and quickly as they can.
The guy, impassive and scary, puts the trombone case down on the bar and slowly opens it.
Very deliberately, he pulls out a machine-gun.
The people in the bar breathe a sigh of relief and go about their business.