By Douglas J. Rowe
The Associated Press

The hilarious acorn doesn't fall far from the hilarity tree.

"I think it's genetic," Tina Fey says, explaining where her acerbic humor comes from. "My mother is really dry," and her father and older brother were huge comedy aficionados.

In middle school, she enjoyed getting laughs when she cracked a joke. So by the time she was 13, she knew she wanted to "define myself, put it out there, that I was kinda funny."

Twenty years later, Fey has defined herself as the first female head writer of NBC's Saturday Night Live, co-anchor of the show's "Weekend Update" and an Emmy winner. Now she's putting it out there as a first-time screenwriter with Mean Girls.

The movie stars Lindsay Lohan (Freaky Friday and Confessions of a Teenage Drama Queen) as Cady, a naive girl who falls in with her new high school's coolest, prettiest, most treacherous triumvirate of girls, called the Plastics. Their skills at backstabbing would make those who surrounded Julius Caesar proud. Eventually, Cady's original (uncool, outsider) friends wonder: Et tu, Cady?

Fey recognized the potential for a funny film in a New York Times article that became the best-selling book Queen Bees & Wannabes: Helping Your Daughter Survive Cliques, Gossip, Boyfriends and Other Realities of Adolescence.

Plays a teacher

"The whole subject matter just interested me because I think some of those things that girls do to each other is sort of hilarious - even though it's painful for the girls who go through it," says Fey, who plays a math teacher in the movie.

She also finds it ingenious "that girls somehow at a certain age know how to screw with each other. ... It all rang true to me."

Not that she was a mean girl herself - or ever viciously picked on. But she recalls how girls stuck to "invisible rules" to keep each other in place.

"For example, you never say anything positive about yourself. Like you would never, ever be like, 'Hmmm, I look good today.' Because you would get smacked down so fast. And, just say, if your best friend hates some girl, you hate her too. That's part of friendship. You will help ostracize her, because your friend doesn't like her."

Mostly, Fey was "a happy-go-lucky nerd who operated in my own little social situations outside of the cool people. ... The boy-crazy part of Cady's character is certainly me, too."

Could she do it?

She's married now - to Jeff Richmond, who provides special musical material for SNL - and wanted to see if she could write a successful film "because I'm 33 and I gotta figure out if I'm gonna have a family some day (and) what kind of lifestyle can I set up for myself."

By Sunday, when the preliminary box-office figures are released, she'll find out if she gets a second chance at a screenplay, she cracks.

Lorne Michaels, the creator and longtime boss of Saturday Night Live and producer of Mean Girls, thinks Fey's movie is in the tradition of those high-school-angst movies that people still fondly remember years later, such as Fast Times at Ridgemont High, Sixteen Candles and The Breakfast Club - but with a modern twist. Kids these days use 2004 technology - instant messaging, cell phones and three-way calling - to communicate and mess with each other, he notes.

Such movies have universal appeal, he says, since high school is one of the few experiences everyone has in common. "That's a tough period in people's lives. And it leaves its mark on people."

No matter what happens with Mean Girls, Fey will be busy when SNL returns earlier than usual next season to capitalize on the presidential election.

At the same time, Fey will continue developing a series for NBC. It'll be a comedy, and that's about all she can promise at the moment, adding: "It won't be Law & Order No. 8 ... Law & Order: Pedestrian Unit."