Justin Bieber suffered a concussion Thursday when he walked into a glass wall during a concert in Paris, even briefly fainting after finishing the show. "I guess me and glass windows just don't go together," Bieber told TMZ. Two years ago he ran into a revolving glass door. Thursday's performance was a "secret" one for fans at a skyscraper. "So basically, um, you know … there [was] a glass wall behind me but there's a railing behind the glass," he said. "And so, um, I went to reach for the railing and hit my head on the glass."