In perhaps his most memorable cameo since donning a furry dolphin suit at a Flaming Lips performance, Justin Timberlake joined Mick Jagger and the rest of the Rolling Stones onstage during the veteran rock band's set at the concert for Toronto on Wednesday night. The afternoon kicked off on a low point for Timberlake when a concertgoer's sign questioning the singer's sexuality made it to the jumbotrons for about 15 seconds. Timberlake took to the stage with an obvious awareness of audience cynicism, beginning his set with a small attempt to mitigate the crowd's frustration: "This will be over before...