Mega-sized rock ‘n’ roll stadium shows are not known for giving fans a chance for intimate interaction with their idols. So I thought I’d witnessed about as good an example as you could get of bridging that gap at Bruce Springsteen’s terrific 5 July show in Vienna, where a pleading young woman bobbing on her boyfriend’s shoulders in the sea of bodies near the stage got the Boss to play (for the first time in Europe) his achingly beautiful, rarely performed version of Tom Waits’ “Jersey Girl.” (See how here.)

But three Czech guys have managed to top that. As Radio Prague reports, guitarist Stepan Etrych, bassman  Cyril Strejc and drummer Michal Simek - collectively a tribute band called U2 Pop Tarts - attended U2’s 18 July show in Berlin bearing signs advertising their ability to play “Angel of Harlem.” When the band swung into that rollicking tribute to Billie Holiday (from their Rattle and Hum album), Bono spotted the trio and brought them onstage to back him up, casually informing the crowd, “This is an experiment.”

Here’s the kicker: This impromptu gig before 80,000 screaming fans was the Czech trio’s first public performance. They’d only ever played in rehearsal, polishing their chops while they searched for a singer who could channel Bono. Having played with the real thing, they might just have leapfrogged to the top of Prague’s considerable revival-band heap.