Adrian Grenier got back to his roots over the weekend at Brooklyn Bowl in Williamsburg. The “Entourage” star, who was known to play the bongos while a student at Bard College, joined his new-wave folk band, the Honey Brothers, for an hourlong set. “At one point, he brought a drum to the center of the stage and danced around while beating on it,” says a spy. “He also played recorder for one song.” Grenier left the venue wearing a furry lumberjack hat and a Velvet Underground T-shirt.