Knock-knock joke

Tasman learned the famous banana/orange knock-knock joke from an episode of Backyardigans. Well, she sort of learned it. Most of you probably know how the joke is supposed to go. (If not, watch it on YouTube.) Here's how it went this morning, prompted by the fact that she was eating a banana for breakfast.

T: [knocking on her tray] Knock knock.
S: Who's there?
T: Banana.
S: Banana who?
T: Knock knock.
S: Who's there?
T: Orange.
S: Orange who?
T: Knock knock.
S: Who's there?
T: Orange.
S: Orange who?
T: Knock knock.
S: Who's there?
T: Are you going to say banana?