Rock legend Joan Jett, surprised the crowd when she joined Ke$ha on stage for a memorable performance of her hit song "Bad Reputation!"

Joan didn't didn't let us down with her red leather outfit and killer guitar riffs. The collaboration ended with fireworks above the iHeartRadio Music Festival stage and the crowd singing "Happy Birthday" to the rock icon.

Check out the performance below! 

PHOTOS: Ke$ha performs at the iHeartRadio Music Festival 2013