Before television shows like The Office and Parks and Recreation cemented the mockumentary in the minds of millions, there was Christopher Guest. He didn’t invent the genre, but he’s widely recognized as one of its most influential practitioners, and for my money, there’s none better. I’ve watched Waiting for Guffman and Best in Show more times than I can count. But the one that has stuck with me the most, the one I quote at the slightest provocation, is This Is Spinal Tap. If you’ve seen it you...