There have been 37,258 teen comedies released since Ferris Bueller's Day Off first hit movie theatres in 1986.

Okay, maybe it just feels like there have been that many. So let's be real: Tales of high school hijinks may come and go, but Ferris Bueller's Day Off is eternal.

Decades after its release, John Hughes's Chicagoland celebration of skipping school and seizing the day maintains an enthusiastic fan community. Ferris freaks have created maps and guides for reenacting Ferris's day off from start to finish. They write academic essays dissecting the teen comedy's Marxist overtones. But most of all, they love a good conspiracy theory.

The Fight Club Theory

The most famous Ferris Bueller's Day Off fan theory is The Fight Club Theory, a.k.a. The Durden Derivative, which posits that Ferris is just a figment of Cameron's imagination and Sloane is a girl that Cameron's crushing on, big time, but has never actually talked to. Creepy.

Believers in The Fight Club Theory, named after the 1999 film (and 1996 book) in which Brad Pitt plays soap maker Tyler Durden, claim that it explains the movie's more preposterous moments. How can Cameron, Ferris, and Sloane cover so much of Chicagoland in a single day? That's easy: Because it's all in Cameron's head. Doesn't it seem weird that the entire town of Shermer rallies around some high school kid with a cold? Not if Ferris is just a symbol of how badly Cameron wants someone, anyone, to save him from his unhappy home life.

According to the theory, Cameron conjures up Ferris and Sloane in order to deal with the fear and neglect dealt out by his materialistic dad, Morris. When Cameron accidentally totals his father's Ferrari at the end of the movie, he no longer needs Ferris and Sloane, so he tells them to leave, and they do. Makes sense, doesn't it?

Not really. If it's all in Cameron's noggin, why is Rooney there? What about Jeanie? How come Cameron's missing in action for the end of the movie? The Durden Derivative doesn't offer up any solid answers. It doesn't even match up that well to Tyler Durden's role in Fight Club. Still, it's fun to speculate.