Why?

My niece is going through a cute phase where she asks "Why?" whenever you say anything. Apparently she got it from my nephew, although I don't remember him doing it.

So a conversation might go something like this:

Caz: "What's that?"
Me: "A tie."
"Why?"
"Because I went to church."
"Why?"
"Because it's Sunday."
"Why?"
"Because it's the first day of the week."
"Why?"
"Because of the Romans or the Gregorians, I'm not sure."
[ponders...]
"Are you busy?"
"No."
"Daddy's busy."
"I see. Are you busy?"
"No, I'm Caz."