Green Day’s frontman, enjoying some down time from the band’s touring commitments and song writing, happened to be at Slim Jim’s Liquor Store located in Angel, north London. UK Heavy alternative rock band Borderline Toxic was performing a set when they decided to include a cover of one of Green Day’s most well known and popular hits “Basket Case” from their break-out record Dookie from 1994.

Unable to resist the temptation, Armstrong jumped onto the stage to accompany Borderline Toxic front-woman Kerry Glass-much to the enthusiastic surprise of those in attendance.

Judging by the video the band posted across their social media platforms, the London based rockers were visibly thrilled to be joined spontaneously by a man the members consider to be a punk rock hero. Posting later about the event on social media, the band expressed, “the moment your band gets joined on stage by your childhood idol to sing their own song with you…Billie Joe Armstrong, thank you, you legend!”

The excitement and joy of the occasion was not just Borderline Toxic’s to revel in, as Armstrong himself looks to have had an exuberant time performing his own smash hit. The band also took to social media to quip, “when you walk into a pub and the cover band starts playing your song.” Green Day also shared video of the performance across their social media accounts.

Styling themselves as a rock and roll dive bar, Slim Jim’s pride themselves on supporting local London bands, providing them with a stage and atmosphere to rock out. Featuring an impressive selection of whiskies, the bar features live DJ events and, occasionally, international acts- although a surprise cameo from an artist like Armstrong is probably as good as it could ever get for any small bar venue.

Green Day have reportedly began working on a new album. Work has been commencing in Los Angeles and London, which could explain Armstrong’s presence in the city over the weekend. What would be their 14th studio record, the album has a hopeful release date of sometime in 2024.

Green Day took their highly anticipated Hella Mega Tour on the road last summer with support from Weezer and Fall Out Boy, playing stadiums and arenas throughout the United States and United Kingdom. After releasing their last studio album, The Father of All Motherfuckers in 2020, fans will be delighted at the quick turnaround between releases of new music.