Mean Girls tells the story of Cady Heron (Lindsay Lohan), a girl who's been homeschooled in Africa since she was 4, and is going to an American public high school for her junior year. On her second day, she makes friends with a gothic girl (Lizzy Caplan) and a gay boy (Daniel Franzese). But on her third day, three popular girls (Rachel McAdams, Lacey Chabert, and Amanda Seyfried) known as the Plastics, invite Cady to eat lunch with them. The gothic girl, Janice, hates the leader of the group, Regina, so after Regina humiliates Cady at a Halloween party, she recruits Cady to spend more time with the Plastics and try to take down Regina. But the more time she spends with the Plastics, the more of a "mean girl" she becomes. Eventually, when the whole school turns against her, she has to set things right.
There is strong sexual content for a PG-13, including a lesbian couple kissing at a party and a few perverts who want to "butter muffins" and see girls in the nude. The language isn't too bad: one use each of "hell" and "effing", and several uses of "bitch", "slut", "ass", "crap", and "damn". Two instances of teen partying, including one where Cady drinks to the point where she vomits.