A duck walks into a gas station store and asks the shopkeep, "Got any toilet paper?"
The keep tells the duck, "No, this is a gas station. We ain't got no toilet paper."
The duck walks into the station the next day and asks, "Got any toilet paper?"
The keep, slightly miffed this time, tells the duck, "I told you yesterday, this is a gas station. We ain't got no toilet paper."
The duck walks into the station the day after that and asks the same question.
The keep, clearly incensed this time, shouts, "I told you once, I tell you again, we ain't got no freakin' toilet paper! Now if you show up here again I'm gonna nail your feet to the floor to teach you a lesson!"
The duck returns the next day and asks the keep, "Got any nails?"
"No."
"Got any toilet paper?"