Cameron Diaz and Justin Timberlake

What was high school like for Cameron Diaz? "Super-easy," she told TVGuide.com at the Bad Teacher premiere in New York City. "I already knew it wasn't the real world and there was another world outside."

The Office's Phyllis Smith, who's co-stars in the film, says she wishes she'd had more "chutzpah" in school and wasn't so shy. Kirstie Alley also would've liked to be less timid. Her advice for her high school self: "Lighten up ... sleep with more guys!"

Watch our video below for more from the celebs on the red carpet. Plus: Which co-star does Jason Segel have a bigger crush on: Cameron Diaz or Justin Timberlake?