Underachiever
Polly Shulman writes, in a review of "Everything and More: A Compact History of Infinity" by David Foster Wallace (originally on Salon but received by me via Powell's Review-A-Day listserv):
The greatest thrill I remember from my girlhood -- better than my first kiss, first airplane flight, first taste of mango, first circuit around the ice rink without clinging to a grown-up's sleeve -- was the heart-lifting moment when I first understood Georg Cantor's Diagonal Proof of the nondenumerability of the real numbers.
Choke. Cough. No comment.

What? That's a GREAT proof! I've always prefered Gödel's proof of his incompleteness theorem myself, but probably because it's just so subversive in nature ... or was that not your point?
I'm sure it's one of your favorite girlhood memories as well, then. ;)
Absolutely!