“A duck walks into a store and asks the manager if he sells grapes. The manager says no, so the duck leaves. The next day the duck goes back to the store and asks the manager if he sells grapes. The manager says, “NO, we don’t sell grapes,” so the duck leaves the store. The next day the duck goes back to the same store and asks the manager if he sells grapes. The manager is furious now and says, “NO, WE DO NOT SELL GRAPES! IF YOU COME BACK AND ASK IF WE SELL GRAPES AGAIN, I’LL GLUE YOUR BEAK TO THE FLOOR!” The next day the duck goes back to the same store and says to the manager, “Excuse me, do you sell glue at this store?” The manager says, “No, we don’t sell glue.” The duck replies, “That’s good. Do you sell grapes?”