Knock Knock!!

Who is there?
Banana
Banana who?
knock knock!
Who is there?
Banana
Banana who?
knock knock!
Who is there?
Orange
Orange who?
Orange you glad I didn't say banana again?

sometimes he forgets to say orange and he could go all day with the banana part.

His new thing is asking
"what is so funny?" when you are laughing at his joke.
then he says "say, your knock knock joke!"