Rob Reiner’s directorial debut, about a British heavy-metal band on the long way to the bottom, turns the mockumentary genre all the way up to 11. Although other examples of the form, such as The Rutles: All You Need Is Cash (1978) and A Hard Day’s Night (1964), preceded it, This Is Spinal Tap unleashed the floodgates of pop-culture satire and cemented the template for the genre. Christopher Guest, Michael McKean and Harry Shearer, who wrote the script, though largely improvised, star as the hapless bandmates. In the ultimate hilarity, the film so expertly skewered rock excess that many show-biz insiders thought that Spinal Tap was an actual band. U2’s The Edge declared, “I didn’t laugh, I wept. It was so close to the truth.” And kids, just remember: “It’s such a fine line between stupid and clever.” — Laura Emerick

Rated: R