"That'll be five dollars", says the bartender, and the guy throws 20 quarters onto the floor.

Reluctantly, the bartender picks up the coins and serves the beer.

The next day, the guy comes into the bar, asks for a beer, throws 20 quarters onto the floor, etc.

The next day, again.

On the fourth day, he asks for a beer, and hands the bartender a 10$ bill. The bartender takes advantage of his chance for revenge, throws 20 quarters onto the floor and yells "here's your change asshole!"

The guy looks down at the coins and says: "I'll have another beer, please."