When aliens take over the planet and attempt to decipher our culture, what on earth will they make of "Scary Movie 4"? Will they find it a disconcerting masterpiece of the avant-garde? An inexplicable fantasia of multiple realities, grotesquerie and flagrant bowel dysfunction?

If they get to it having first absorbed the various movies and celebrity scandals that the parasitic franchise feeds on — this year's checklist includes "Saw," "The Village," "The Grudge," "War of the Worlds," "Brokeback Mountain," "Million Dollar Baby" and Tom Cruise freaking out on Oprah's couch — well, they'll still think we're out of our minds.

In either case, I welcome them with open arms so long as they arrive, as they do here, in the form of giant iPods blasting "Karma Chameleon" — minus the "Destroy Humanity" playlist, please.

The fun of "Scary Movie 4" is that it isn't a movie at all. Organized on the principle of parody, not plot, driven by gags and cultural feedback, it's an exercise in lowbrow postmodernism, a movie-movie contraption more nuts than Charlie Kaufman's gnarliest fever dream. It's cleverly stupid.

Hit or miss, complete nonsense, the very definition of disposable: this is the price one pays to watch the exposition from Steven Spielberg's "War of the Worlds" mashed up with Sir Mix-a-Lot's "I Like Big Butts," Shaquille O'Neal trapped in "Saw" and the funniest Viagra overdose in the history of meta-cinema.

"Scary Movie 4" is rated PG-13 (Parents strongly cautioned). Naughty jokes and rough language are spoken. Bodies are much abused and loudly emptied of their waste.