6 Insane Fan Theories That Actually Make Great Movies Better | Cracked.com
Ferris Bueller's Day Off Was All in Cameron's Head
The Theory:
Cameron creates Ferris in his mind. Ferris is the total opposite of Cameron: he's fun, spontaneous and has a loving family and foxy girlfriend. At the beginning of the film, the imaginary Ferris convinces a bed-ridden Cameron to "borrow" his dad's Ferrari 250 GT California and cruise all over Chicago. Given Cameron's crushing social incompetence, it's likely that Sloane is fictional too and represents a girl that he has a crush on.
This theory explains the more fantastic elements of the film. For example, the whole city of Chicago rallies around the "sick" Ferris. This represents Cameron's miserable home life and how he yearns for friends and family who give a shit. Or, perhaps Bueller is a guy Cameron knows but isn't friends with, and his fantasy is based on what he imagines life to be like for the "popular" kids at school--everything is easy and the world revolves around them.