Superstar

Let’s say right out front that ”Saturday Night Live”’s Mary Katherine Gallagher — the klutzy Catholic schoolgirl/horndog played to nervous, armpit-smelling perfection by Molly Shannon — is plenty reason enough to stay home on a Saturday night. The question is, can Shannon’s spastic pratfalls sustain nearly 90 minutes? ”It’s not ‘Wait until she gets to the buffet table and watch what happens!”’ insists director McCulloch, a ”Kids in the Hall” alum.

”It’s the story of an underdog.” The underdog is Mary Katherine, who’s dying to get a Hollywood-style smooch from campus hunk Sky Corrigan (Ferrell). When a school talent contest offers the winner a chance to be a film extra, the geeky celeb wannabe decides that’s her ticket to a luscious lip lock.

Shannon fleshes out the character by giving audiences a glimpse into Mary Katherine’s home life with her overbearing grandma (Johns) and expresses her budding sexuality by tongue-kissing a tree. ”Molly’s character is almost better on film,” says Ferrell, who does double duty as Sky and a mega-mellow apparition of Jesus Christ. ”Molly really gets to show off her acting chops.”

And was Shannon nervous about the hit-or-miss proposition of taking an ”SNL” sketch to the big screen? ”My initial thought was, Why does everything have to turn into a movie?” she says. ”But Mary would never [say no]. She’d be like, ‘Where do I sign?’ She’d be everybody’s whore.” BUZZ FACTOR: 5