A duck walks into a bar and says, "Pint of bitter please barman.."
The barman says "Sorry, we don't serve ducks here. You'll have to leave."
The next day, the duck walks in and says, "Pint of bitter please mate.."
The barman says "Look. I've told you, we don't serve ducks here. Get lost!"
The next day the duck walks in and before he can say anything, the barman says "Right. I've had enough of you. Ask me one more time for bitter and I'll nail your beak shut!"
The duck looks at him then says, "I'd like a hammer please barman."
The barman looks confused and says "We haven't got any hammers?!"
The duck considers and then says "A bag of nails please, my dear chap."
the barman says, "We haven't got any nails"
So the duck says "A pint of bitter please.."