Knock, knock?

My youngest daughter, age 2, is into "knock, knock" jokes right now. She has made one up that goes like this:
DD: "Knock, Knock!"
Me (or whoever): "Who's there?"
DD: "Orange."
Me: "Orange who?"
DD: "Orange you!"
Me: "Orange me?"
DD: "You an orange!"
Me: "I'm an orange? What are you?"
DD: "Funny!"