The Critter is at that stage where she is bound and determined to figure out how everything works. I've been pretty impressed at how she applies logic and the power of (four-year-old) deduction to determining the why's and what's of things.
I don't remember exactly what we were talking about: maybe something to do with where do babies come from or whether or not perfluorocarbon deoxygenates during partial liquid ventilation (the answer: it's time dependant). Whatever the topic was, I was suitably impressed again at her reasoning and told her so.
Me: Wow - that's pretty good. You're a smart cookie.
Critter: Yep. That's because I have hard brains.
Me: You have what?
Critter: Hard brains. Some people have hard brains. Like me.
Me: What about me? Do I have hard brains?
Critter: No. You have short brains.
Me: Short brains?
Critter: Yeah. 'Cause you're a boy.