The Strokes brought out surprise guest Charli XCX to perform “Take It or Leave It” during the band’s headlining set Saturday at the Outside Lands festival. You’re new queen of everything, Charli XCX.” The group and the singer — who headlined the previous night at the San Francisco fest — then launched into the Is This It? closer:“Charli motherfucking XCX,” Casablancas said after the surprise performance, circling back to their sales battle. Charli is next scheduled to headline the U.K.’s Reading and Leeds festivals, while the Strokes will jet off to Japan next weekend for the Summer Sonic festivals in Tokyo and Osaka.