A guy walked into a tavern and sat down on a barstool. He ordered a beer and a shot glass of whiskey. The bartender was surprised to see him place the shot glass into the pocket of his overcoat. The man proceeded to drink his beer, then reached into his coat pocket and removed the shot glass, empty.
He ordered another beer and shot glass of whiskey, and again placed the shot glass into his coat pocket. Again he removed the glass empty, then ordered another round.
Overcome by curiosity, the bartender asked the man why he kept putting the shot glass into his pocket.