Whose line is it anyway?

My niece, Eva, is now a little over four years old, and has just got into jokes in a big way. She understands the structure of jokes, she understands that they're funny, but — and this is the thing — she has absolutely no conception of why jokes are funny. None whatsoever.

So, for instance, she's discovered this old gem:

Knock knock!
Who's there?
Banana.
Banana who?
Knock knock!
Who's there?
Banana.
Banana who?
Knock knock!
Who's there?
Orange.
Orange who?
Orange you glad I didn't say banana?

Hilarious as it is, I'm sure we can all agree, but it gains a whole new level of hilariosity when Eva starts developing new jokes around the template, effortlessly drawing handy everyday objects into her improvisation. Thus:

Knock knock!
Who's there?
Glass.
Glass who?
Glass you glad I didn't say banana?

Knock knock!
Who's there?
Mouth.
Mouth who?
Mouth you glad I didn't say banana?

And so on. For a while.

The interesting thing is that Eva appears to find all these new versions every bit as funny as the original, laughing and giggling copiously. She clearly has no idea of what the joke is, but that doesn't stop her laughing at it, and the laughter really is genuine. Fascinating.

That, however, is as nothing to what happens when you combine her new-found love of joke-telling with her long-established outright obsession with princesses, fairy tales, and all things Disney.

Why did Sleeping Beauty go to work?
I don't know, why did Sleeping Beauty go to work?
Because she's so beautiful and lovely and I really love her.

You had to be there.