United Kingdom, Jan. 30 -- Rachel McAdams "didn't know how hated she would be" for playing school bully Regina George in Mean Girls.

The 47-year-old actress starred alongside Lindsay Lohan, Lacey Chabert, Amanda Seyfried, Lizzy Caplan, Daniel Franzese, Tina Fey and Tim Meadows in director Mark Waters' 2004 teen comedy.

In the film, Lohan plays Cady Heron, a 16-year-old girl who transfers to a public high school after being homeschooled her whole life in Africa who carries out a plan to destroy the clique of popular girls The Plastics; Regina (McAdams), Gretchen Wieners (Chabert) and Karen Smith (Seyfried).

McAdams admits she wasn't prepared for Mean Girls to become a pop culture phenomenon nor the level of hatred film fans felt towards...