Making good on its promise to sully the name of America’s educators, the new film “Bad Teacher” is full of mean-spirited humor centered around one highly self-involved instructor, whose less than professional demeanor is a forced to be reckoned with. Directed by Jake Kasdan, this spiritual sequel to the popular “Bad Santa” is 89 minutes worth of blue humor and raunchy sex. The film makes sure to delivering on these primal urges. Everything else is another story.

Cameron Diaz stars as the titular bad teacher, a woman named Elizabeth Halsey whose biggest goals in life include marrying a wealthy guy and getting an expensive boob job. After her engagement is broken off, she concocts a plan to woo the school’s new substitute teacher, Scott Delacorte (Justin Timberlake), a product of old money and the fast track to the aforementioned boob job. Standing in her way is Amy Squirrel (Lucy Punch), the school’s resident overachiever, who’s out to foil the plan.

If “Bad Teacher” ends up being the death knell for the hard-R comedy trend, it will be because the film simply isn’t creative. Sure, it can be funny—but only just so. Hearing and seeing such rampant vulgarity on the screen used to be, at one point, a source of release. We marveled at the audacity. Now, crude humor has become something of a crutch. Diaz, who has never shown much in the way of real acting prowess, is given the simplest of instructions here: Act slutty and swear a lot.

In other words, anybody could do this. Though it sounds unfair, it’s unequivocally true: “Bad Teacher” is visually uninteresting, relies heavily on its screenplay and possesses the thematic depth of an episode of “Blue’s Clues.” Aside from its bright supporting cast, there isn’t an ounce of craftsmanship to be found. Welcome to the comedy of paint-by-numbers.

The only revelation at play here is Timberlake, who, after successful stints as host of Saturday Night Live, continues to showcase his surprisingly deep comedic chops. His character is nothing short of naive and is, in fact, the complete antithesis of what we perceive Timberlake to be—as in, the ultra-suave, effortlessly cool and charismatic lady killer. The only thing Timberlake and Delacorte share is their wealth and good looks.

As a result, the character’s naivety becomes a sort of in-joke for the audience, thanks to the incongruity that arises between the character and the actor who plays him. Kasdan is wholly aware of this and reaps it for all it’s worth, making it the single smartest directorial decision in the entire film.

Timberlake, meanwhile, approaches the role with conviction but retains the kind of self-awareness Jerry Lewis once employed. He plays the character with boneheaded earnestness and isn’t averse to hamming it up, defying his perceived urbanity. By playing against his type, the former pop star reaches moments of high humor and skirts a realm of acting reserved only for the greatest of comedic performers.

Unfortunately, the same can’t be said for the rest of the cast. Jason Segal, who has proven to be a formidable comedic presence in a number of films and television shows, is woefully underused as the hapless gym teacher. Other assorted cast members—including Phyllis Smith of “The Office” as a dopey sidekick and Punch as the chief rival—play a mere second fiddle to an obtuse Diaz.

It’s a shame, too, considering how frequently funny Smith and Punch can be. Both actors bring a number of idiosyncratic quirks to their characters and, not unlike Timberlake, never shy away from looking ridiculous. In terms of shaping the tone for the film, the supporting cast truly does the heavy lifting while Diaz is tasked with simply being crude and looking sexy.

In regards to its crudeness, “Bad Teacher” could be a sign that the hard-R trend of comedy could be wearing out its welcome. Though it worked in the past—some of the most memorable moments in recent cinema include Steve Carrel’s swear-laden wax job in “The 40-Year-Old Virign” and actor Ken Jeong leaping, nude, out of a car in “The Hangover”—the Era of Raunch looks like it’s beginning to waver.