This Is Spinal Tap (1984)
I couldn't remember enough about the movie to remember if I'd ever seen it. It seemed such a stock film ("ours go to 11") that I must have seen it before. So I got it from Netflix, and watched it.
I remember now that I had seen it, and that it was, regrettably, forgetable.
Seemingly well made for its day, it's a mock reality show about a fictitious rock band on a come-back tour across the US. The music, of course, is over the top; it's a combination of late-70's rock and early-80's hair metal, with a blend of "city name band" ballad, all played under a styrofoam skull.
Band tensions rise and fall, the manager quits, the lead bassist quits, the lead singer's girlfriend leads the band in a direction as dictated by the zodiac...
Kudos to Michael McKean and Christopher Guest and the rest of the band for their performances and efforts, but in the end, it's hard to tell where the parody is supposed to be.