Tina Fey (search) was a mean girl in high school, and she's the first to admit it. "Technically, I was a jealous girl," says the "Saturday Night Live" (search) co-head writer, Weekend Update anchor and chief hottie in glasses.
"But because I was jealous, I was mean."
It's the sort of teenage pettiness that Fey plays for laughs in her movie "Mean Girls," which opens Friday.
"High school girls are ingenious in how they sabotage one another in these invisible, unseen, hurtful ways," says Fey, 33, who wrote the movie and has a supporting role as a math teacher.
"The way they mess with each other is so clever and intricate."
Back in the late 1980s, Fey and the other "AP-class brainiac nerds," as she called her clique, used to sit together in the lunchroom at suburban Philadelphia's Upper Darby High School, making up nasty nicknames for their classmates.
The metalheads with stringy hair were the "Hammers," Fey recalls, "because they broke the ice at parties," usually with some crazy stunt like a belly flop over the coffee table.
The popular, preppy girls were the "Laura Ashley Parade," and the prettiest girl in school was "Banana-Boat Boobs."
"Her boobs sort of curved down and then - swoosh! - pointed back up," Fey recalls.
"I know that was really scraping the bottom of the barrel, insult-wise. But I was super-jealous of her, and dealt with it by being sarcastic behind her back."
But it was after reading Rosalind Wiseman's (search) 2002 self-help book, "Queen Bees and Wannabes: Helping Your Daughter Survive Cliques, Gossip, Boyfriends and Other Realities of Adolescence," that Fey realized teenage girls were still as vicious as she had remembered.
Inspired, she took some of the book's lessons and mixed them with the sort of characters you'd meet in classic teen movies like "Sixteen Candles."
Her movie stars Lindsay Lohan (search) as Cady, a basically nice 15-year-old who gets sucked into an epic catfight with her high school's Queen Bee - a girl, who, at least on the surface, is also Cady's best friend.
In real life, Fey never competed at that level of popularity.
She says she was a Lisa Simpson type - a good student who did plays, worked on the yearbook and once hit a game-winning, solo-shot home run to win a playoff game for the Upper Darby softball team.
"I was very obedient," Fey says, but she also stirred up trouble with a notorious satire column for her school's newspaper, which she wrote under the pseudonym "the Colonel."
Though Fey was honing her comic skills in high school, she had gotten an early start at home with her brother, Peter, who's eight years older.
"I always did 'SNL' skits for Tina, like John Belushi doing the Samurai," recalls Peter, a Web site managing editor for the QVC home-shopping network.
Fey's father, Donald, a retired grant writer for the University of Pennsylvania, and her mother, Jeanne, a homemaker, used to do comedy routines around the dinner table.
But Fey always had the family's oddest imagination.
"When she was about 7, she drew this street scene of people walking along, holding hands with huge chunks of Camembert and Cheddar," her brother recalls.
"At the bottom, she wrote, 'What a friend we have in cheeses!'"
After finishing her theater degree at the University of Virginia in 1992, Fey cut her comedy teeth with Chicago's famous Second City troupe before getting the call up to the "SNL" big leagues in 1997. She soon discovered that the 17th floor of 30 Rockefeller Center, where the show's writers work, is a bit like high school itself.
"[Former head writer] Tim Herlihy hazed me the third week I was here," Fey recalls. "I told him I had an idea for the opening sequence, and he was, like, 'Oh, you're ready for that, huh?' I was, like, 'shuh-rink.'"
But when Herlihy left the show two years later, Fey took over as one of two head writers, making history as the first woman in the job.
Now she is the one who hazes other writers - "I like to break them down, Lou Gossett Jr., style," she jokes - but more important, she has revitalized the show. Ratings are up, and thanks to Weekend Update, the fake "SNL" newscast she does with Jimmy Fallon, Fey has become a star - and an unlikely sex symbol to geeky boys across America.
"Tina's beautiful, but she doesn't emphasize it, because of the glasses," says Mark Waters, who directed "Mean Girls."
"Every guy who's not the football-playing type thinks they have a shot with her. They're like, 'Hey, she's brainy like me.'"
Fey's dirty secret, however, is that she doesn't always need glasses - "only for driving and watching a movie," she says.
The idea of being a sex symbol embarrasses Fey - "I always assume people who say that are being ironic," she says - but it didn't stop her from writing a scene into "Mean Girls" where she takes off her shirt and shows some bra and bare tummy.
In her first scene, she walks into class, spills a cup of coffee down her front and peels her shirt off.
The studio wasn't thrilled about the skin. ("They thought it didn't set the right tone for the movie," Waters says.) But Fey wanted it to establish her character as a bumbler.
"We went with this gag because it's original, and also because we couldn't resist the idea of Tina's picture winding up on one of those celebrity-skin Internet sites," he says.
Fey wants full disclosure about that scene, however - "We used the magic of CGI [computer-generated imaging] on it," she says.
Waters did some special-effects touch-ups to her belly in the editing room.
"I have a brown birthmark on my side - and he took that out," she says.
"I should have had him draw in a set of abs while he was at it."