Anyone who has seen Green Day live will have witnessed the break in the set, during which Billie Joe plucks members from the audience to play a cover of Operation Ivy’s Knowledge.

Operation Ivy were part of the same Gilman Street scene (centered around the club at 924 Gilman Street) in the San Francisco East Bay as Green Day, and while they only existed for two years and one album before imploding, their album Energy is crucial punk-rock listening, as Billie Joe points out.

“We actually played [Knowledge] the original way it was recorded the other day! I was like, ‘Let’s do it like Operation Ivy did it.’ We played this small club in Los Angeles and we did it and everybody f**kin’ freaked out! Energy by Operation Ivy is probably in my top five favourite records of all time.

"I was there when it came out, I was friends with those guys when it came out, and I was part of that scene. It hit me right at the right time: I was, I think, 17 when that record came out, and I just have a link to it. Green Day opened up for Operation Ivy on their last two shows that they ever played, and it meant the world to me. The politics still stand up to this day: Operation Ivy were like my Clash.”