Just for Laughs

Here's what I heard from the kids today, totally silly. Here it goes:
-Knock, knock.
-Come in!!
-No your supposed to say "Who's there?", let's try again
-Okay.
-Knock, knock.
-Come in!!
-You have to say "Whos's there?".
-Why would I say "Who's there?" when I know it's you?
-Oh, never mind.... (and walks away)

Maybe it was funnier when it happened, but I just had to share.
m.