A duck walks into a shop. He asks the shopkeeper, "Got any duck food?" The shopkeeper says, "No."

Next day, the duck comes back, and asks the guy, "Got any duck food?" The shopkeeper says, "No, and if you ask me that one more time, I'll nail you to the wall by your feet!"

Next day, the duck comes back. The shopkeeper eyes him suspiciously. "Got any nails?" the duck asks. "No," comes the reply.

(pause)

"Got any duck food?"