Cheap Thrills is a nasty little excursion into the cesspool of human nature that easily lives down to its title, writes Kurt Loder. It's gross and bloody, but it has a jaunty air. The movie looks a lot better than it needs to, and it's a lot more fun than its grisly specifics might suggest. Come for the carnage, stay for the laughs. And don't get too attached to the little white dog.