Mean Girls (2004)

Cady Heron is a cultural blank slate when she first sets foot on the grounds of North Shore High School in a small town outside of Chicago, Illinois. After living in Africa, Cady, now a junior, has no idea how "wild" things can be in civilization until she crosses paths with one of the meanest species of all, the "Queen Bee," who at this particular high school is the cool and calculating Regina George. But Cady doesn't just cross paths with this Queen Bee--she really stings her when she falls for Regina's ex-boyfriend Aaron Samuels. Now Regina is set to sting back by pretending to still like Aaron so he won't go out with Cady, all the while pretending to be her friend. With no choice but to use the same M.O. to stay in the game, the "Girl World" one-upmanship escalates until the entire school gets dragged into a first-class mean-fest.