Duck in a Bar
So this duck walks into a bar, waddles up to the front of the bar, looks at the bartender and says, "Hey bartender, got any grapes?" The bartender says, "No, I don't have any grapes. This is a bar, we serve liquor, not fruit." So the duck leaves.
The next day the same duck walks into the same bar, waddles up to the front and says to the bartender, "Hey bartender, got any grapes?" The bartender says, "I told you yesterday, we don't have any grapes. This is a bar, not a fruit stand." So the duck leaves.
The next day the same duck walks into the bar again, waddles up to the front of the bar, and says to the bartender, "Hey bartender, got any grapes?" By now the bartender is really annoyed with this stupid duck asking for grapes, so he says, "No, I don't have any grapes and if you ask me again, I'll nail your beak to the bar."
The next day the same duck walks into that same bar, waddles right up to the front of the bar, looks at the bartender and says, "Hey bartender, got any nails?" The bartender says, "No." So the duck says "Good, got any grapes?"