It's late afternoon in a low-key Manhattan diner, and Tina Fey, Saturday Night Live's first female head writer, is happily submitting to the pop psychology of ''28 Fab Quizzes'' featured in a recent issue of Teen magazine. They are fluffy little personality tests that range from ''Are you what you eat?'' (apparently, Fey is ''strong, like a jawbreaker'') to ''Who's your dream guy?'' (Clay Aiken, it turns out. ''I would totally have a crush on Clay''). Fey, looking lovely even without the trademark dark-framed glasses she wears on ''Weekend Update,'' is eating this stuff up. ''I'm doing so good on this!'' she cracks between sips of chicken orzo soup. But when she tackles ''Friend or foe?'' which promises to determine if a pal is ''for real or just a flake,'' she gives up. '''You hardly ever disagree,''' she reads, frowning at the superficial definition of friendship. She closes the magazine. ''You can disagree with your friend!''
Of course you canin adult world. But in teenage-girl world, where a single misinterpreted glance can result in nasty, full-on social wars? Not so much. Fey, 33, is somewhat of an expert on the subject of ruthless adolescent maneuvering: It's the heart of her first screenplay, Mean Girls, a comedy starring Lindsay Lohan (Freaky Friday) as a former homeschooler who is thrown into a public high school in 11th grade and ends up out-eviling the supreme diva (The Hot Chick's Rachel McAdams). Based on Rosalind Wiseman's sociological nonfiction book from 2003, Queen Bees & Wannabes..., the film costars Fey herself as Lohan's math teacher, as well as fellow SNLers Amy Poehler, Tim Meadows, and
Ana Gasteyer. In Fey's mind, it's ''a new kind of SNL movie,'' more in line with A Mighty Wind than, say, A Night at the Roxbury. ''When I see all those Christopher Guest movies,'' she gushes, ''I'm like, Oh, man! Why can't me and my friends do something like that?''
Okay, but why set the project in the land of miniskirts and three-way calling? ''The stuff that Rosalind talks about rang true to me,'' explains Fey, who spent her teen years in Upper Darby, Pa., as a member of the drama club, tennis team, choir, and coeditor of the school newspaper. ''I remember that kind of behavior. I was cowardly mean. I would be home with my friends, just endlessly talking about whoever left the room.'' She pauses and breaks out her wry ''Update'' smile. ''That's the main reason you get talked about: You accidentally leave the room.'' Plus, she continues, ''I feel like there's something innate in women, the ability to be cruel and competitive with each other in this weird, invisible way.'' (Mean Girls' girl-on-girl crime involves vicious gossiping, boyfriend stealing, and tricking others into gaining weight.) ''These girls are ingenious in the ways that they mess with each other. And I wanted to write about it.''
So in mid-2002, Fey turned to SNL godfather Lorne Michaels, who signed on as producer and helped persuade Paramount to option Wiseman's book before it was even published. (Fey discovered Wiseman's work through a New York Times Magazine article.) ''Making a movie with somebody is like driving cross-country,'' Michaels says. ''You have to have a lot of respect for them because there's going to be times when you want to not be in the car. Tinashe's brilliant. She has a standard and she's not going to compromise it.''