Yes, the holidays can be a harrowing experience, but is surviving them any harder than sitting through a Ben Affleck movie? With rare exceptions — and they're getting rarer all the time — watching the puffed-up “Armageddon” star do his thing seems like a reasonable pretext for sticking one's head in an oven. That, incidentally, is how an elderly character dispatches herself in the opening moments of Affleck's sourly unfunny holiday farce “Surviving Christmas.”

Above-the-line casting and octogenarian suicide aren't the only things conspiring against this predictable, indelicate, punishingly trite product of Mad Lib movie producing. There's also the small matter of its premise. “Surviving Christmas” is about the havoc visited on an otherwise normal family by an unwelcome, obnoxious house guest. Keep in mind, this is a genre which government researchers — using lab mice and cutting-edge clinical methods — have scientifically proven to be lethal in large doses. If you don't believe that, try watching “What About Bob?” and “Duplex” back to back, and see how tufts of ripped-out hair gather at your feet.

Affleck seems to have overdosed on silly pills as Drew Latham, a smarmy, cynical Chicago ad man (yes, a cynical ad man — believe it!) who makes the big bucks convincing stressed-out Americans to drown their holiday headaches in alcoholic eggnog. Estranged from his family, Drew wants to blow off Christmas and take his girlfriend to Fiji, but she spits at the idea and calls him shallow. Strangely, she never thinks to invite Drew to spend Christmas with her family — just one of the many vacations from common sense booked by hack screenwriters Deborah Kaplan and Harry Elfont (“Can't Hardly Wait”).

As if by magic, Drew becomes a Christmas true believer overnight, returning to his childhood home and paying the family that currently lives there, the Valcos, a hefty $250,000 sum to tolerate his presence and help him recapture the holiday magic of his youth. The Valcos are a joyless bunch. The parents, bearded wrench-monkey Tom (James Gandolfini) and menopausal ice-queen Alicia (Catherine O'Hara), are mulling divorce, and their teenage son Brian (Josh Zuckerman) spends his days and nights huddled in front of Internet porn.

The more we see of Drew, the less “Surviving Christmas” makes sense. Here's a guy who supposedly runs a million-dollar ad agency, and yet is so childishly deluded that he insists on calling two strangers “mom” and “dad”? So fantasy-prone that he types up Christmas Eve scripts for the Valcos to act out? So indifferent to his own physical well-being that he seems quite pleased with Tom for braining him with a snow shovel? In trying to synthesize the screwball tit-for-tat of “What About Bob?” and other similarly themed comedies, director Mike Mitchell (“Deuce Bigalow: Male Gigalo”) has careened wildly into a dipstick parallel universe where even the broadest rules of comedy don't apply.

To top it off, the Valcos end up having an attractive adult daughter (Christina Applegate) who Drew only learns about later, as if throwing a superficial romantic subplot in his lap somehow redeems the character from his idiotic quirks. Sorry, no deal. Maybe if Roberts agreed to — I'm just spitballing here — burn every existing DVD copy of “Deuce Bigalow,” we could talk turkey.

Until that fine day, the only thing absolving “Surviving Christmas” of its sins is an edgy, if under-utilized, performance from O'Hara (“Waiting for Guffman”) and a meager selection of pithy one-liners. The movie even manages to short-change our appetite for candy-puckered Christmas sentimentality, which is no great loss, given the movie's exotic mid-October release date. Who knows? If Affleck and his alcoholic eggnog leave theaters fast enough, they could be on home video for the holidays.