1994’s Dookie is often regarded as both Green Day’s best album and one of the greatest punk albums of all time; thus, it’s risky for another band to cover something from it, especially if frontman Billie Joe Armstrong is watching. That’s precisely what happened to English alt-rockers Borderline Toxic last night (May 13), and lucky for them – and the excited crowd – Armstrong felt like helping out.

READ MORE: Green Day Albums Ranked

The group was performing at Slim Jim’s Liquor Store in Islington and decided to try their hand at Green Day’s beloved “Basket Case.” Suddenly, Armstrong jumped on stage to share vocal duties with lead singer Kerry Glass, and both the group and their fans were understandably awe-struck and excited.

Last night, Green Day posted a short clip of the performance to Instagram, commenting: “When you walk into a pub and the cover band starts playing your song @slimjims_liquorstore.” Likewise, Borderline Toxic tweeted earlier this morning (May 14): “Billie Joe Armstrong from @GreenDay got on stage with us last night at our favourite London dive bar!!!! Brb screaming/crying/spewing.”

They also posted a slightly different video to Instagram, rejoicing: “The moment your band gets joined on stage by your childhood idol to sing their own song with you… in your favourite dive bar!! Billie Joe Armstrong… @greenday !! THANK YOU, YOU LEGEND! This was the first band to get me into rock when I was 11 years old and I’m honestly just so made up. brb crying/screaming/spewing.”

Expectedly – because social media is social media – reactions have been mixed on the Green Day side, especially regarding Borderline Toxic drummer Pete Ray Biggin. For instance, one Green Day Instagram follower wrote, “Drummer killed it, and not in a good way,” while someone else defended him: “[D]rummer was probably nervous guys give him a break feelin Billie joe Armstrong just walked in.”

Fair point.

Endearingly, Borderline Toxic's socials garnered all positive feedback, such as one person declaring: “Gosh! You all were on cloud 9!!!!! Simply incredible!!!!!!! So happy for you all!”

You can view those posts/clips below, so be sure to let us know what you think of their impromptu collaboration!

Also, you can check out Green Day’s upcoming tour dates here.

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