At a time when hip-hop has become obsessed with bombast, Skinny Jeanz and a Mic brings rap back to basics. The tricky programming of “So Dope,” “Turnt” and “Colorz” echoes both the booming minimalism of early rap pioneers like Schoolly D, as well as the vertiginous thrills of Timbaland. “Bunz” even partakes in Miami Bass, a long overlooked genre that jerking is helping to revive.