When she read the script for first-time feature director Justin Simien's campus satire Dear White People, Tessa Thompson (For Colored Girls) was convinced that only she could play Sam White, the fiery DJ of a radio station at a fictional Ivy League college. Submitting her audition tape for the film, a breakout at last winter's Sundance Film Festival, she included not only the requested scenes but all of Sam's barbed on-air segments, which tweak the supposedly PC, mostly white student body. The actress was particularly drawn to Simien's one-liners, some of which he'd tested out on Twitter. Her favorite: ''Dear White People Using Instagram, you have an iPhone and you go on hikes, I get it.''