A duck walks into a convenience store and asks the worker: “Do you have any grapes?”

The worker says no, and the duck leaves.

The next day, the duck returns and asks: “Do you have any grapes?” The worker again says no, and the duck leaves.

The day after that, the duck walks into the store again and asks: “Do you have any grapes?”

The worker screams at the duck: “You’ve come in here the past three days and asked if we have any grapes. I told you no every time as we don’t have any grapes! I swear if you come back in here again and ask for grapes, I’ll nail your webbed feet to the floor!” The duck leaves.

He returns the next day. This time he asks: “Do you have any nails?”

The worker replies: “No.”

And the duck says: “Good! Got any grapes?”