Celebs arrive at the 2012 Billboard Music Awards held at the MGM Grand Garden Arena on May 20, 2012 in Las Vegas, Nevada-Pictured: Justin Bieber
Photo: Splash News
And unlike the revolving-door incident of May 2010, this tango with a glass wall — backstage at a concert in Paris — gave poor Bieber a concussion. He even passed out for a second! But then he trotted back out onstage and finished the show, because Justin Bieber is a goddamn professional. Take that, glass.