“Bad Teacher” is exactly the one-joke movie that you probably expect it to be, but there are enough variations and shadings of that one joke to sustain its brief running time – just barely.
Cameron Diaz plays … a bad teacher. She secretly sips airline-size booze bottles during class, doesn’t bother to learn her students’ names and figures that showing them movies about education like “Stand and Deliver” and “Dangerous Minds” is just as good as educating them herself. Because you see, she’s not teaching English at a suburban Chicago middle school for the deeply rewarding experience of shaping young minds. She just needs enough cash for a boob job, which she thinks will help her land a rich husband.
Like the far superior “Bad Santa” from 2003, the key source of laughs here is the subversion of an authority figure who’s supposed to be trustworthy, reliable, even honorable. And, like Billy Bob Thornton in that earlier film, Diaz just goes for it. Director Jake Kasdan (“Walk Hard: The Dewey Cox Story”) photographs her as if she were a vixen in a Whitesnake video, and Diaz revels in a role that lets her be brazenly sexy and inappropriately funny all at once.
Her character, Elizabeth Halsey, isn’t a mean or cruel person, per se; she’s definitely selfish and scheming, morally devoid and perpetually intoxicated. But sometimes, twisted little nuggets of kindness inadvertently pop out, as in her admonishment of a nerdy, lovesick student to get over the pretty, popular girl in class. She’ll never like him, Elizabeth tells him, figuring she’s doing him a favor by being honest with him now, at a young age.
And you know what? She’s got a point.