The movie also uses situational irony in the form of the "burn book". The "burn book" is a book that the "plastics" have where the write mean stuff about all the girls that they go to school with. The book ends up being seen by all the girls that are talked about in the book. This is situational irony because in reality people know that it is wrong to have a book made specifically to bash people that you go to school with.
The movie Mean Girls is a genius satirical work that targets how girls treat each other in high school. The movie as a whole is an over exaggeration of how girl treat each other once the reach high school. It is an attempt to open the eyes of society of how the way some girls behave is acceptable because they are popular. The movie exposes the idea of what it means to be a popular girl in high school society and what you have to be to make that happen.