Duck walks into a bar, jumps up on the barstool and says, "got any duck food?".
Bartender says, "no we don't have any duck food. We don't serve your kind. We have beer, wine and whiskey. Now get out of here, before I nail your bill to the bar!"
The duck waddles out.
Next day the duck comes back in, jumps up on the barstool and says, "got any nails?".
Bartender says, "no we ain't got any nails".
Duck says, "Got any duck food?"