Every day this duck walks into the grocery store and waddles up to the cashier "Got grapes".
Cashier say "No, get out of here"
After a week of the duck asking "Got grapes", the cashier flips "We don't have grapes, you come in here again and I'm gonna nail your bill to the counter!"
Next day the duck walks in "Got Nails?" cashier says "No" ............ Duck "Got Grapes?"