Video: Jessie J - 'Who's Laughing Now'

Jessie J gets the last laugh in the video for “Who’s Laughing Now,” the latest U.K. single off her debut Who You Are. In the tongue-in-cheek clip, the bobbed-haired singer reminisces on her days as an outcast in grade school when she was teased by the popular kids. But a young Jessie gets payback, wreaking havoc on the cafeteria and theater, and hosing the mean girls with a fire extinguisher.

The British chart topper, who will open for Katy Perry in the U.S. this fall, dresses up as different characters including a teacher, lunch lady, and janitor. Watch her rule the school.