Billy Joe Armstrong of Green Day surprises a cover band in London.Photo: Green Day/Instagram; Tim Mosenfelder/WireImage

https://www.instagram.com/reel/CsMv1bBpGCs/?utm_source=ig_embed&ig_rid=9c1e4852-4ada-4b90-8197-d30c898c7fa7. Green Day/Instagram; TEMPE, ARIZONA - FEBRUARY 25: Billie Joe Armstrong of Green Day performs during the 2023 Innings Festival at Tempe Beach Park on February 25, 2023 in Tempe, Arizona. (Photo by Tim Mosenfelder/WireImage)

Billie Joe Armstrongjust gave aGreen Dayfan the time of her life.

The pop-punk legend, 51, surprised a cover band in London while they were playing Green Day’s 1994 smash “Basket Case” during a concert, and the whole thing was documented in a new viral clip.

“When you walk into a pub and the cover band starts playing your song,” a post from the official Green Day Instagram account read.

In the video, the bandBorderline Toxiccould be seen jamming out to the breakthrough Green Day hit when Armstrong darts up to the stage at Slim Jim’s Liquor Store.

The band reflected on the fun shortly after the gig, writing on Instagram that the moment they played with the Rock and Roll Hall of Famer was one of “pure joy.”

Billy Joe Armstrong.Timothy Hiatt/Getty

CHICAGO, ILLINOIS - AUGUST 15: Billie Joe Armstrong of Green Day performs during the Hella Mega Tour at Wrigley Field on August 15, 2021 in Chicago, Illinois. (Photo by Timothy Hiatt/Getty Images)

“Thank you Billie Joe Armstrong a million times over for this unforgettable experience 🥹 so glad I got to share this moment with a band I love, in my favorite bar, with all our mates… singing with my childhood idol,” Borderline Toxic shared. “What a time 🥹”

Other clips from the moment show Armstrong sharing a mic with the band’s lead vocalist, Kerry Glass.

“It’s only just sinking in that I used to always wish it was me they’d pick to get up on stage at the live gigs, haha, wishful thinking,” she wrote. “Could never imagine the man himself would be getting up on our gig. I honestly couldn’t be happier 😢😍”

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Just last June, the Green Day frontman revealed he’d be “renouncing” his citizenship from the United States during a recent concert in London, following theSupreme Court’s ruling to overturnRoe v. Wade.

“F— America. I’m f—ing renouncing my citizenship. I’m f—ing coming here,” Armstrong told concertgoers, adding that there was “too much f—ing stupid in the world to go back to that miserable f—ing excuse for a country.”

“Oh, I’m not kidding, you’re going to get a lot of me in the coming days,” the “American Idiot” musician added.

Armstrong does have afew gigs coming up in the States,and recently celebrated the 25th anniversary of the band’s albumNimrodin January with a special re-release. The updated LP features14 unreleased demosand additional unreleased live material.

source: people.com