Audiences tuning into the FireAid benefit concert for Los Angeles on Thursday night (Jan. 30) were surprised with an early treat when pop superstar Billie Eilish made a surprise appearance alongside Billie Joe Armstrong and the rest of Green Day for a stirring opening performance.

Two of the evening top-billed acts, Billie Eilish and Green Day, decided to sneak in an onstage duet. As the band geared up to play their beloved 21st Century Breakdown track “Last Night On Earth,” Eilish shocked viewers by picking up a microphone ahead of her set.

The concert will also be screened live at select AMC Theatres and and Regal Cinema locations in the U.S. If you will be on the move, iHeartRadio, the national audio partner for the event, will also feature the FireAid concert across over 860 radio stations in the U.S., digital platforms, and the iHeartRadio app.