YG live: With an assist from DJ Mustard, young California rapper proves his power

He'd already gotten them to shriek and shout and bounce their butts. So near the end of his set at the Fillmore Silver Spring on Friday night, YG initiated a group confession. It came during "Momma," an apology to his mother for the uncounted misdeeds he raps about in other songs. "I know I did wrong," YG shouted. "I know I did wrong," hundreds of fans shouted back. And for a moment, a Friday night in the club was a Sunday morning in the pews.