Director Rob Reiner’s funniest film, this side-splitting rock mockumentary chronicles the less-than-triumphant return to America of legendary British heavy-metal group Spinal Tap. As the band members who don’t spontaneously combust or die in gardening accidents, Christopher Guest, Harry Shearer and Michael McKean deliver spot-on performances; the many terrific cameos include Patrick Macnee as Sir Denis Eton-Hogg and Rob Reiner himself as documentary filmmaker Marty DiBergi.