A duck walks into a bar. He goes up to the bartender and asks, "got any grapes?"
"No," says the bartender. "We don't have any grapes."
A few minutes later, the duck comes back. "Got any grapes?" he asks again.
"I already told you," says the bartender. "We don't have any."
A few minutes pass, and the duck is back again. "Got any grapes?"
The bartender is starting to get annoyed. "No!" he says. "We don't have any grapes! If you ask me again, I'm gonna nail your feet to the floor!"
The duck returns a few minutes later. The bartender is about to kick him out when he asks, "Got any nails?"
"What? No!"
"Got any grapes?"