Pop-punk legend Billie Joe Armstrong once said, “I think it’s your own choice if you turn from an angry young man to a bitter, old bastard.” While the 51-year-old Green Day frontman has certainly matured since the band’s 1994 breakoutDookie, he is far from growing bitter and old. Armstrong stays current in a variety of ways, including by keeping in touch with today’s music. Recently, the Oakland, California native enjoyed the biggest musical moment of the decade (possibly century)—Taylor Swift’s “Eras” tour.

Taylor Swift kicked off the European leg of her billion-dollar “Eras” tour in May. On Sunday (June 2), the “Fortnight” singer kicked off the first night of a four-show run in Lyon, France.

During Sunday’s show at the Groupama Stadium, Swift announced the crowd had broken the venue’s all-time attendance record for a female artist. During Monday’s show, the 14-time GRAMMY winner announced, “You broke that record.”

Billie Joe Armstrong was there to help shatter that record. The “Basket Case” singer gushed about his experience in an Instagram post Monday (June 3.)

Armstrong declared the tour’s production—along with Swift’s voice, songwriting and entertaining capabilities—”great.”

“Crazy crowd,” Armstrong wrote. “People even shared with me some friendship bracelets. Thanks a million

The GRAMMY winner flashed the aforementioned friendship bracelets in a photo. One read, “sexy baby,” a lyric from Swift’s 2022 hit “Anti-Hero.” The other declared, “a**hole outlaw,” from the Midnights bonus track “Hits Different.” Both messages feel equally fitting for the man who wrote “something about billie joe armstrong going to the eras tour and having a good time makes me happy,” one user wrote on X/Twitter.

One Instagram user was bold enough to ask the question on every emo kid-turned-Swiftie’s mind. “Green day and Taylor swift collab when?” they commented.

Which Other Celebrities Have Attended the ‘Eras’ Tour?
Swift’s mega-successful “Eras” tour has forever altered the landscape of live music. The U.S. Travel Association estimates that the tour has generated more than $5 billion for local economies. It’s no wonder that even celebrities want in on the action. Billie Joe Armstrong is far from the only A-lister to come along for the “Eras” ride.

Swift’s boyfriend, Travis Kelce, discussed on his New Heights podcast dancing alongside the “Shake It Off” singer’s longtime friend Gigi Hadid and her rumored boyfriend, actor Bradley Cooper.

Even former Swift nemesis Katy Perry couldn’t resist dropping by the show when the “Hot N’ Cold” singer was in Sydney, Australia. And she even sang along to “Bad Blood!”