The bartender says “No.”
The duck leaves. The next day the duck walks back into the bar, sits down and asks the bartender, “Hey barkeep, got any grapes?”
Angered by the duck the bartender walks over to the duck and says, “Look pal, this is a bar. We serve drinks, not grapes! Next time you ask for grapes, I’m going to nail your bill to the bar.”
So the duck leaves. The next day the duck walks into the bar, sits down and asks.
“Hey barkeep, got any nails?”
The bartender smiles and says, “No.”
So the duck says, “Got any grapes?”