A duck walks into a store and askes the clerk "do you have any grapes" and the clerk says "no, we don't sell those here".

So the Duck walks in the next day and askes the clerk again "do you have any grapes" The Clerk, says sternly "I told you yesterday, we don't sell grapes here".

The Duck goes back into the store the following day and askes for grapes and the clerk replies "I already told you, NO, we don't, and if you come back in here and ask for grapes again I'm going to nail your feet to the floor".

The duck goes into the store the next day and asks "do you have any nails?" the clerk repies "no" and the duck goes "good, do you have any grapes?"