Surrealist Knock-Knock Jokes

Adam: Knock knock who's there!
Me: Umm... Who?
A: Banana! (giggle)
M: Banana who?
A: Knock knock who's there?
M: Who?
A: Banana! (more giggling)
M: Banana who?
A: Knock knock who's there?
M: Who?
A: Orange! (even more giggling)
M: Orange who?
A: (giggling obscures words) Banana! (pause) Mommy, you say "knock knock!"
M: Okay. Knock-knock, who's there?
A: Who?
M: (unable to think of a single knock-knock joke) Umm... Banana?
A: No! How about tomato?
M: Tomato.
A: No! How about motorcycle?
M: Motorcycle.
A: (immoderate giggling)

How about motorcycle, indeed.