What's in a a name

KK: Thaddy's name is Thaddy cuz he's little.
Me: Oh? What will his name be when he gets big?
KK: KK.
Me: Then what will your name be?
KK: When I get little my name will be Thaddy.
Me: What about when you get bigger?
KK: Then my name will be Fifi.