Iron Maiden’s Bruce Dickinson and Billie Joe Armstrong Perform

Talk about a rock crossover we didn’t know we needed. On Thursday night at San Francisco’s Comic-con weekend kick off party, Iron Maiden frontman Bruce Dickinson surprised fans and joined Billie Joe Armstrong‘s the Coverups onstage.

The rock icons dove into an impassioned cover of Mott the Hoople’s classic “All the Young Dudes,” with Armstrong playing his signature red Les Paul as he and Dickinson harmonized. Both Dickinson and Armstrong have a storied history with the song: Dickinson recorded a version for his 1990 solo album Tattooed Millionaire, while Armstrong credited David Bowie, who wrote track, on Green Day‘s 2009 hit “21 Guns,” which shares a similar melody.

Earlier in the night, the Coverups had set the stage on a high note with covers of rock classics, including Cheap Trick’s “Hello There” and the Ramones’ “I Wanna Be Sedated.” The cover band is one of Armstrong’s many side projects.

For the unacquainted, Dickinson’s presence at the Comic-Con event makes more sense when you remember he wrote a 12-issue comic book series as part of his solo concept album The Mandrake Project. On Friday, the rock star will be signing copies of The Mandrake Project: Year Two, a new collection that details the road to the album-comic. “We’ve performed with Green Day quite a lot of times, but we’ve been on separate stages in separate bands,” Dickinson told a CBS affiliate on Friday. “I more or less remember the words,” he said, adding, “It was good fun.”