Knock knock

A friend of mine told me a knock knock joke today, that I proceeded to tell the kids.

The joke:
Knock knock.
Who's there?
Interrupting Duck.
Interruptin...
QUACK!

Ha Ha.

However, in Katie's hands, retelling it, it came out like this:

Katie: Knock Knock.
Me: Who's There?
Katie: Interrubbding Duck.
Me: Interupting Duck Who?
Katie: Quack.

I pointed out that it's not funny unless she interrupts me saying "interrupting duck."

So, she retells it:

Katie: Knock Knock.
Me: Who's There?
Katie: Interrubbding Duck.
Me: Interup...
Katie: Um...Ooh...Uh...um...er...QUACK!
Me (Laughing): you forgot the word QUACK??

So, not exactly Vaudeville material, but funny to listen to...