There are so many offensive messages to be taken away from Bad Teacher, and yet, it has this sort of undeniable charm that seems to be congenital in all Cameron Diaz movies (except The Sweetest Thing). Getting to the core of the film's unabashed promotion of certain stereotypes, Elizabeth Halsey's (Diaz) chief goals in life are to get married to a wealthy man and to have her tits enlarged.
Passing her days until that moment as a teacher at John Adams Middle School (JAMS), Elizabeth's life course is thwarted when her fiancé unexpectedly calls off the wedding (a droll fight that involves her bringing up how annoying it was to listen to him complain about the death of opera).
Forced to return to John Adams after the summer is over, Elizabeth responds apathetically to the enthusiastic reception of her co-workers, especially her "hall mate" Amy Squirrel (Lucy Punch, who delivers a very convincing American accent). Right off the bat, Elizabeth establishes her teaching style as cinephilic, showing everything from Stand and Deliver to Dangerous Minds to Scream (for a second there, you thought there was a theme, didn't you?).
While Elizabeth is content to let her students delight in this form of learning, Mrs. Squirrel immediately approaches her about these lax machinations, causing Elizabeth to respond with lines like, "I don't know what you heard, but I don't eat muff pie." And, by the way, part of what makes Bad Teacher so amusing is Diaz's deadpan bitchery, particularly when contrasting this role to her other, more sugary sweet ones.
Some moviegoers may have a hard time with suspending disbelief about the number of debauched actions Elizabeth is able to get away with (e.g. smoking "medicinal" marijuana in front of a student, writing criticisms on her students' tests that say things like, "Are you fucking kidding?", and stealing a state test), but, then again, if you really think about it, the school system is as shitty as they say--Illinois definitely included.
Therefore, it shouldn't surprise the audience that a school district will pay pretty much anyone willing to "watch" thirty or so junior high kids for six hours a day. This is, of course, yet another derogatory truism that screenwriters Gene Stupnitsky and Lee Eisenberg throw at you. So, besides the rampant generalizations of Bad Teacher, you should also beware the dry humping sex scene between Diaz and Timberlake. It's a bit weird, but I suppose a testament to how the two have managed to jump over that hurdle of awkwardness since their breakup. Maybe Timberlake really is destined for the silver screen with professionalism like that.