A foot-long scrotum hanging out of an old man’s briefs turns out to be the enduring image from this anemic bad-taste comedy, starring Johnny Knoxville in octogenarian disguise and directed by Jackass veteran Jeff Tremaine. Conceptually, it’s a cross between Borat (embarrassing situations created in public and captured on hidden camera) and Bad Santa (with Jackson Nicoll as the old man’s eight-year-old grandson and fellow troublemaker). There’s one great sight gag—seated on a children’s ride outside a discount store, Knoxville is catapulted through a plate-glass window—but most of the others are painfully trite (a corpse knocked out of a casket at a funeral, a mechanical bed that goes crazy). Onlookers occasionally glance into the camera, a pretty good sign that people are hip to these prankster movies now and just play along.