Knock Knock

Tyler has been learning lots of jokes lately and is starting to get good at telling them. Not wanting to miss out on the laughs, Daphne has also been telling the same knock knock joke repeatedly. She has told us the following "joke" at least 20 times the past week and giggles every time even though we are not sure why it is funny:

Knock knock.
Who's there?
Banana.
Banana who?
Banana cha cha dance! (this is when Daphne starts giggling)