The writers in Hollywood are not mathematicians. If they were, they could make the traditional gross-out comedy formula work. Unfortunately, Hollywood failed again with “”The Sweetest Thing,”” a pathetic attempt to duplicate the belly-laughs generated by “”There’s Something About Mary.””

The primary factors in this farce are Christina (Cameron Diaz), Courtney (Christina Applegate) and their hapless friend Jane (Selma Blair): three beautiful babes looking for love.

While all three women are willing to settle for “”Mr. Right Now”” over true love, the shenanigans are getting old. Diaz’s character unwittingly grabs Mr. Right’s butt at the most opportune moment. She doesn’t realize it at the time, so what follows is a girly, half-hearted combination of “”Road Trip”” and “”My Best Friend’s Wedding.””

Ever since her breakthrough performance in “”The Mask,”” Diaz has shown her comedic caliber. She worked magic when playing off the comedic talents of Jim Carrey and Ben Stiller. But without the funny men helping her, Diaz flounders.

For “”The Sweetest Thing,”” Diaz is forced to rely on an old standby: comedic timing. Unfortunately, that’s about all she’s got. It’s hard to pinpoint where Diaz fails. It may be somewhere between her wet-dream sequence and when she gets soaked and poked in a public restroom — in other words, throughout the film.

This movie’s redeeming moments are rare. It is unusual to see a woman successfully use a urinal, yet Applegate somehow achieves the feat. Applegate also reveals to the male audience why women go to the bathroom in groups.

Like all gross-out comedies, “”The Sweetest Thing”” goes for the gags in every way possible. All the bases are covered, from oral sex and the compromising positions of a zealous couple to nasty leftovers of all kinds. Yet it’s not the raunchy scenes that will leave audiences reeling, it’s the choppy editing of the film that makes viewers wonder what happened to the punchlines.

“”The Sweetest Thing”” is by all accounts a chick flick. Men may love watching Diaz shake her ass, which she does often, but the squeals and giggles are bound to drive anyone nuts. About as fluffy as cotton candy, “”The Sweetest Thing”” makes an equally fleeting impression.

The Sweetest Thing

**

Starring Cameron Diaz and Christina Applegate

In theaters April 12

Rated R