THE BEST scene in the teen comedy "The DUFF" occurs when the title character finds out what DUFF actually means.

Her name is Bianca (Mae Whitman), a high school student whose blissful nerd-dom is shattered when she realizes, all at once, what social status is and that she doesn't have any.

Up to that point, she's a smart, confident girl who doesn't think it odd in the least that she wears Crocs and coveralls and that her two best friends are two of the most beautiful, fashionable girls in school.

Then a guy tells Bianca she's the DUFF - Designated Ugly Fat Friend.

Bad moment for Bianca, but a good moment for Whitman, whose face goes from confused to crestfallen to horrified. You see the floor of a happy childhood dissolve beneath her feet and watch poor Bianca fall into the teen abyss of self-doubt and self-awareness.

In, I hasten to add, a mostly funny way.

Funny thanks to Whitman, and the punchy, "Mean Girls"-ish script by Josh Cagan, who also wrote the screenplay for the well-received "Bandslam."

The movie is glib and willfully superficial but also smart at times about teen social stratification, which frazzles Bianca. She gets jealous, separates from her friends, then agrees to a makeover directed by next-door neighbor Wesley (Robbie Amell), a handsome jock who needs compensatory help in science class.

One scene has hunky Wesley offering to give Bianca kissing lessons, leading to what I'm fairly sure is an improvised gesture by Whitman that makes the moment amusing and memorable.

"The DUFF" ends up as a romance with notes of teen-girl empowerment, and while it's never original, it's always good-natured. The finale, which sets up as a potential prom-night catastrophe, turns "Carrie" on its head and trades telekinetic carnage for a redemptive kiss.