Cameron Diaz is so good when she's bad. In this trailer from her new comedy Bad Teacher, in which she stars with ex-boyfriend Justin Timberlake, Diaz drinks, smokes pot and swears up a storm.

Diaz plays Elizabeth, a burned out middle school teacher who's over her job and looking to find a rich man to take care of her. When new substitute Scott (played by Timberlake), shows up, she thinks she may have found her ticket out. (Watch the clip above.)

Diaz and Timberlake, who had a messy split in 2007, seem to have gotten over their past. And Timberlake's current girlfriend, Jessica Biel has said she's "super-excited" to see the film.