A duck walks into a bar. He hops up on a stool and asks a bartender "got any grapes?" The bartender replies "No, this is a bar. We don't have grapes here." The duck leaves.
The next day he comes in to the same bar, hops up on the same stool and says "Got any grapes? The bartender angrily replies "NO! we don't have any grapes. I told you yesterday that this is a bar, now if you ask me one more time, I'm gonna nail your feet to the floor!" The duck leaves.
The next day the duck returns and hops up on the same stool. The duck asks "Got any nails?" The bartender, puzzled says "No, why?" The duck replies "Got any grapes?"