A duck waddles into a bar, hops up onto the stool and asks, "Got any grapes?"

The bartender glares at him. "Does this look like a grocery store? No grapes here."

"Okay," says the duck. He hops off the stool and waddles out.

Three days in a row, the duck comes into the bar and asks for grapes. Finally, the bartender is at the end of his patience, and explodes, "For the last time, this is a bar! We do not have grapes! The next time you ask for grapes, I'm going to nail your bill to the bar!"

The duck says, "Okay," and waddles out of the bar.

The next day, in comes the duck. As he hops up onto the stool, the bartender glares suspiciously. The duck asks, "Got any nails?"

The bartender is fed up. "This is not a hardware store, either! We have no nails!"

The duck looks him in the eye and says, "Okay...Got any grapes?"