A duck walks into a bar and says, "Hey, you got any duck food?" The bartender says, "No, we don't got any duck food. Get outta here." So the duck leaves.
The next day, the same duck is back, "Hey, you got any duck food?" The bartender says, "No, I told you we don't got any duck food. Now get outta here!" So the duck leaves.
The next day, again, the same duck is back, "Hey, you got any duck food?" The bartender says, "No, goddammit! I told you we don't got any duck food! You ask me that again, I'm gonna nail your beak to the bar!" The duck leaves.
The day after that, the same duck comes back, again. He says to the bartender, "Hey, you got any nails?" The bartender says, "No, this is a bar. We don't got any nails." The duck says, "Good. You got any duck food?"