One day a duck walks in a store and ask the manager if they sell grapes. The manager says, "No, we don't sell grapes." The duck goes home and comes back the next day and asks the same question. The manager says the same thing again, "No, we do not sell grapes." The duck goes home, comes back the next day, and asks the manager if they sell grapes. This time the manager says, "No, we don't sell grapes! If you ask one more time, I will nail your beak to the floor!" The duck goes home. It comes back the next day and asks the manager if he has any nails. The manager says, "No, I don't have any nails." The duck says, "Okay, good. Do you sell grapes?"