The bartender politely informs the man that it appears that he has already had plenty to drink--he could not be served additional liquor at this bar but could get a cab called for him.
The drunk is briefly surprised then softly scoffs, grumbles, climbs down off the bar stool, and staggers out the front door.
A few minutes later, the same drunk stumbles in the side door of the bar. He wobbles up to the bar and hollers for a drink. The bartender comes over, and still politely--but more firmly refuses service to the man due to his inebriation. Again, the bartender offers to call a cab for him.
The drunk looks at the bartender for a moment angrily, curses, and shows himself out the side door, all the while grumbling and shaking his head.
A few minutes later, the same drunk bursts in through the back door of the bar. He plops himself up on a bar stool, gathers his wits, and belligerently orders a drink.
The bartender comes over and emphatically reminds the man that he is clearly drunk, will be served no drinks, and either a cab or the police will be called immediately.
The surprised drunk looks at the bartender and in hopeless anguish, cries "Man! How many bars do you work at?"