What’s better than one Billie? Two.

Yesterday (January 30), dozens of musicians and thousand of music lovers came together to raise money for the Los Angeles County wildfires. While the FireAid benefir concert lineup was filled to the brim with star-studded entertainers, one moment has users online giddy.

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.

With both the group’s leader Billie Joe Armstrong and Billie Eilish giving their all to the power track, supporters online have praised the link-up as the “Billie reunion” they did not know they needed.

Although Eilish is known for her catchy pop tunes and Green Day’s punk discography was not out of reach for the Oscars winner. But does this mean the recording artists have a secret collaboration tucked away? Probably not. For now, fans of both entertainers are reveling at the moment. As a bonus, it certainly could have directly helped to increase donations for the night.

Watch the full FireAid benefit concert above, courtesy of Netflix.