-Knock Knock
-Who's there?
-Common decency would suggest you should open the door and find out instead of continuing this exchange from either side of a door.
-Well, pardon me for being suspicious but I find it strange that a man would actually speak the words "knock knock" instead of the time-honoured practice of the physical knock. Now are yo going to tell me your name or what?
-No, this joke has lost its momentum.
-OK, good day to you, Sir.
