40 DAYS AND 40 NIGHTS

Zero stars

Don’t waste even one night on this.

Running time: 95 minutes. Rated R(sex, nudity, profanity, stupidity). At theEmpire, the Lincoln Square, the UnionSquare, others.

EASILY the most witless movie released this year, “40 Days and 40 Nights” is soft-core idiocy best appreciated by overstimulated adolescent males in the privacy of their bedrooms.

Would-be heartthrob Josh Hartnett made this embarrassment between his scowling turns as military men in “Pearl Harbor” and “Black Hawk Down” – and it turns out to be even less funny than his previous forays into comedy, “Blow Dry” and “Town and Country.”

The premise is beyond limp.

Hartnett plays Matt, a San Francisco Web site designer who’s having numerous unsatisfying liaisons after being dumped by his bitchy girlfriend (Vinessa Shaw).

After a bizarre conversation with his brother (Adam Trese), a Catholic priest, Matt decides to give up sex for Lent as a curious form of self-improvement.

“Dude!” he announces to a statue of Christ – while another, of the Virgin Mary, winks at him.

But no sooner does Matt take the vow than he meets the tempting Erica (Shannyn Sossasman) in a Laundromat.

The guys at the office, who have a betting pool on how long into the 40-day period he’ll last, are totally obsessed with derailing his promise to abstain from any and all forms of sexual behavior.

The gals – who wear fishnet stockings to work but no bras – are even more determined to lead him astray.

Newcomer Robert Perez’s screenplay – directed with maximum smarm by Michael Lehmann (“Heathers”) – is so single-mindedly crude you wish there were a Society for the Prevention of Cruelty to Actors.

Poor Hartnett is forced to walk around with a visible bulge in a couple of scenes, handcuffed to a bed, spread-eagled in another.

There are even more cringe-worthy sequences involving his boss (Griffin Dunne), who gets some Viagra intended for Matt, and Matt’s father (Barry Newman), who graphically describes post-operative sexual positions over family dinner.

I’m no prude, but “40 Days” surpasses even the recent “Slackers” for unfunny, sexual humor, including a scene where Matt fakes an orgasm.

At least Hartnett gets to play a one-dimensional character. The women aren’t that lucky.

The female characters exist solely as fantasy objects. One miniskirted hottie gets to spread her legs, wide, for the camera – and numerous others jiggle topless.

“40 Days and 40 Nights” is so eyeball-gougingly awful that you’re tempted to give up movies for Lent.