Mean Girls is as bright and shiny as the really expensive white gold hoops that Regina forbid Gretchen from wearing—you know, because hoop earrings are "her thing." Its frames are lively and colorful…just like the student body of North Shore High School itself.
Of course, there is no North Shore High School. Mean Girls wasn't even in filmed in Chicagoland. Instead, most of the shoot took place in Toronto. North Shore's exterior, for example, is actually Etobicoke Collegiate Institute. (Source)
The film also isn't afraid of a fantasy sequence here and there. When Cady first lays eyes on her classmates around the fountain at Old Orchard Mall, for example, she imagines them as wild animals, and we see what she sees.
Later, when Regina dangles Aaron in front of her, we see Cady pounce on her frenemy like a jungle cat. At the end of the film, we see the junior Plastics get leveled by a bus, too. They don't happen often, but these fantastical elements help keep Mean Girls hurtling along with all energy of a teenager.