As any kid who's ever forcibly shot milk through their nasal passages can testify, the key to a great gross joke isn't so much the content as it is the delivery. The proudly crass Bad Teacher certainly has great big gobs of greasy, grimy potential, chief among them its central performance by an exceedingly game Cameron Diaz, but it occasionally fails to nail the dismount. This film from director Jake Kasdan (Walk Hard: The Dewey Cox Story) is exactly what the title says: after getting dumped by her rich boyfriend, a lying, cheating, and perpetually boozing middle-school teacher (Diaz) hatches a scheme to con her school out of enough money to pay for cosmetic surgery, while squaring off against the aggressively cheerful teacher across the hall (a very funny Lucy Punch). Lessons are not learned, thankfully. Although the title and attitude recall the effortlessly filthy Bad Santa, Bad Teacher feels more like a spiritual sequel to Diaz's earlier Sweetest Thing, a women-can-be-gross-too comedy that spent more time congratulating itself on how far it was willing to go instead of actually going there. While Bad Teacher certainly has its number of belly laughs and worthy outrages (particularly during a hilariously awkward love scene between Diaz and a nerded-up Justin Timberlake), it's hard not to end up with a general feeling of missed opportunities. Too often, it toes the bad-taste line, when it should be jumping over it with a rocket cycle. --Andrew Wright