Charli XCX brought out surprise guest and future tour mate Halsey during the singer's Lollapalooza set Sunday to stage a sing-along of Spice Girls' anthem "Wannabe." "You guys like girl power, right?" Charli XCX asked before the
This article originally appeared on www.rollingstone.com: See Charli XCX, Halsey Sing Spice Girls’ ‘Wannabe’ at Lollapalooza