Charli XCX made a surprise appearance during The Strokes’ headlining set at Outside Lands in San Francisco, giving festivalgoers an unexpected collaboration between two major names from different corners of music. They shared the stage through the performance, adding a pop crossover moment to The Strokes’ rock-focused set. Casablancas also referenced the fact that Charli and The Strokes released new albums on the same date, making a lighthearted comment about the overlap during the show.