Green Day's Billie Joe Armstrong joins London covers band in pub
HANDOUTImagine belting out a cover of a song - only to be joined by the lead singer of the original on-stage.
Well, that's exactly what happened to Borderline Toxic.
They were performing Basket Case by Green Day in a London pub when the band's frontman Billie Joe Armstrong made an unexpected appearance.
It's unclear why Billie Joe was having a drink at Slim Jim's Liquor Store in Islington, but it definitely brought the house down.
"Eleven-year-old me panicked," lead singer Kerry Glass tells BBC Newsbeat, after the weekend's performance.
"I think I did three circles just running around the stage until he was like, 'Come on, sing with me'."
Videos posted online, including one on Green Day's own YouTube channel, show Kerry running to the side of the stage as Billie Joe joins the band.
Billie can then be seen launching into the song - from the band's breakout album Dookie - before Kerry eventually gets on the mic with him.
"It took a minute to settle," says Kerry.
"And then I was like, 'You know, I'm going to enjoy every single second of this'."
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Rock fan Kerry says Green Day were one of the first bands to get her interested in the genre when she was just 11 years old.
So when one of her idols got on stage with her it was a big moment.
"I used to sit in my bedroom and listen to all their albums. So I've got zero chill over this. This is amazing," she says.
Kerry says she put her phone away on the night so she could properly experience the moment.
"Honestly, I started getting a bit overwhelmed," she says.
Getty Images"I had to just put my phone behind the bar and I was like, 'I just want to enjoy this moment. I don't want to look at it. I'll deal with it tomorrow.'
"I got about three hours' sleep."
But she says she's been on her "phone ever since" Green Day posted a clip of the performance on their socials.
"The nicest part is people that went to school with and people that used to go to rock clubs when we were younger have got in touch and been like: 'Oh my god, Kerry, that's amazing'.
"That's been the nicest thing."
No-one seems quite sure why Billie Joe popped up in a small London music venue - although he reportedly vowed to move to the UK in protest against changes to US abortion laws last year.
After his cameo Borderline Toxic - who have been played on Radio 1 - continued to play one of their original songs.
"Then we had to follow up with an original song after that - it was wicked," Kerry says.
"I was like: 'Thanks for warming it up Billie Joe'."
