Bad to the bone

Pill-popping nurses. Meth-cooking chemistry teachers. Pot-peddling moms. Homicidal detectives. Drunk daddies. Horrible bosses. It makes simple sense that the generation raised on syrupy, hugging-and-learning fare like “Love Boat” and “Eight Is Enough” would revel in corrupt characters. Rather than watching the same frazzled heroes rise to some grand challenge under duress, we’re treated to crestfallen types who cut corners, lie through their teeth and whine like children, smoking and swearing and driving too fast all the while.

Still, once the nurse passes out on her shift, the chem teacher gets someone killed, and the pot peddling mom gets pregnant with a drug kingpin’s baby, then what? As most people know from their experiences at spring break, writer’s conferences or extended bouts of unemployment, you can only wallow in depravity for so long before it starts to get a little tedious. Then the trick is to make salvation look satisfying – and let’s face it, Jesus himself was hard pressed to fulfill that goal.

This is the big problem with a movie like “Bad Teacher.” You start with a skin-deep concept — she’s a teacher, but she’s baaad! – and you’ve already backed yourself into a corner. Because once your bad teacher has napped during class, swigged from the little bottles of liquor in her desk, puffed on pot in the parking lot, cheated, lied, stolen and written “Stupid!” in red marker all over tests, what’s left?

Which isn’t to deny the inherent entertainment factor of watching a high school teacher ignore the imperatives of her career’s chirpy-nerd culture by showing up to class violently hungover and showing teacher-themed movies (“Dangerous Minds” anyone?) instead of actually teaching. “Bad Teacher” achieves its chuckles in no small part because Cameron Diaz makes a surprisingly convincing self-interested, shallow jerk. After watching Diaz play the sporty guy’s-girl and the lovable, goofy sweetheart for so many years now, it’s refreshing to see her sulking and cussing and rolling her eyes for a change. Not only are most of us about as sick of the plucky, aw-shucks romantic heroine as we once were with the earnest moralism of the ’70s and ’80s, but we’ve heard Diaz’s off-key singing and endured her heartfelt odes to meats on sticks already. Watching her embody a grumbly, self-serving catastrophe is every bit as enjoyable as the movie poster suggests, and it’s a testament to Diaz’s talents that she can make us root for Elizabeth Halsey, an awful person who spends the majority for the movie plotting tirelessly to raise money for a new pair of fake tits.

There’s nothing specifically wrong with the rest of the movie. It meets the minimum requirements to graduate, with some occasional A and B moments along the way. Somehow, though, things never quite transcend the realm of mildly enjoyable. Justin Timberlake shifts gears as dramatically as Diaz here, leaving his nefarious charmer role from “The Social Network” in the dust to play a dorky teacher prone to painfully geeky remarks about the incomparable joys of molding young people into honorable souls. Timberlake makes up for a blatantly Adam Sandler-esque love song with a hilarious dry-humping scene that’s exactly as queasily over-the-top as it should be.

Most of the other characters, though, feel like bland versions of characters from a Christopher Guest film. There’s the geeky principal with a passion for dolphins (John Michael Higgins), the geeky rival teacher who spouts bad puns and wears terrible costumes to spice up her classes (Lucy Punch), and the geeky rule-follower friend who supports Elizabeth’s ambitious quest for boobs but would never dare to color outside the lines herself (Phyllis Smith). Quirky geeks can be amusing, but without a commitment to revealing deeper levels of oddness or reveling in outright madness, you’ve got a succession of look-how-dorky scenes that you could find in any given scene involving the OCD guidance counselor from “Glee.”

If you’re going to make a movie that’s really a farce – because the characters are all caricatures, because the situations aren’t realistic – then it had better be packed with enough jokes or ridiculous situations to keep the audience laughing so loudly they don’t care how plausible the plot is. “Old School,” “School of Rock,” “Talladega Nights” – these are the sorts of movies where you expect pure ridiculousness and jokes and curveballs every few minutes. Instead, “Bad Teacher” features a scene where Diaz washes cars in slow motion, causing a gape-jawed preteen to sport a visible boner. If you really want to watch an extra-long Carl’s Jr. commercial, why bother leaving the house?

Of course, “Bad Teacher” itself is just a snappy pitch with no follow through, the sort of skin-deep idea that can get development executives (and audiences) interested without exerting itself unduly. “Cameron Diaz plays a drunk whore of a high school teacher, and Justin Timberlake is her goody-two-shoes love interest? Where do we sign?” Considering the total lack of a thoughtful plot, considering the dearth of memorable jokes or scenes or characters, “Bad Teacher” really isn’t that bad at all. And look, if you laugh out loud at Carl’s Jr. commercials, definitely go see this movie. But if you don’t, and you still wan to see a charming film about geeky regular folks, rent “Cedar Rapids” and give “Bad Teacher” a pass.