:CADY IS A GIRL:
One day, Cady is invited to sit with The Plastics at lunch in the cafeteria where seating is important and restricted to cliques. Afterwards, Janis and Damian convince Cady to eat lunch with them again, so she can report back to them everything The Plastics say and do. For example, Cady is introduced to "The Burn Book" in which insulting comments are made about the other girls. At the same time, Cady develops a crush on Aaron Samuels (Jonathan Bennett). Gretchen and Karen tell her that Aaron was Regina's ex-boyfriend, and therefore, he is off-limits. Although Gretchen promises to keep Cady's crush a secret, she tells Regina. Devising a plan, Regina offers to help Cady win Aaron. During their calculus class, he invites her to a Halloween party. At the party, Regina finds Aaron and kisses him. Cady is infuriated and decides to leave The Plastics. Janis, however, stops her, convincing Cady to keep hanging out with them so that they can get revenge.
However, Cady has begun to act exactly like Regina, much to Janis' displeasure. As soon as The Plastics kick Regina out of their group, Cady becomes the most popular girl at the school. She throws a small get-together at her house that turns into a huge party. Slightly drunk, Cady tries to make a move on Aaron, but he sees through her, calling her a "clone" of Regina and rejecting her advances. She loses her friendship with Janis and Damian, who now hate her nearly as much as they hate Regina. Regina discovers that "Kälteen" bars make her put on weight, which has been ruining her life (at exclusive clothing store '1 3 5', she is unable to fit into a size 5 dress that she originally intended to wear to Spring Fling). Regina decides to now ruin Cady's life.
Regina gives "The Burn Book" to her principal at school, Mr. Duvall (Tim Meadows), and frames the remaining members of The Plastics for writing it by adding herself to the book, but none of them, so that they are the only junior girls not included. She first makes numerous photocopies of its pages. Distributing these copies around the whole school, she causes all the girls to turn against each other. Outraged, Mr. Duvall gathers all of the junior girls into the gymnasium for an attitude makeover. Cady's math teacher, Ms. Norbury, is asked to take charge of the workshop. The girls are made to confess the bad things they have done and said about their peers.
