That's why Ed Rooney is such a hardass: He knows that the more he enforces rules, the more students like Ferris will rebel. As a result of his rulemeistering, Ferris is a vehicular expert/computer whiz/electrician.
- A creative theory, but the parts where Rooney sadistically mutters to himself about how he's going to ruin Ferris' life so hard doesn't fit in very well.
- It's his job. Doesn't mean he enjoys being torn up by dogs and covered in dirt. You'd probably wanna make Ferris miserable too, after all that.
- Except that he muttered that particular line while sitting in his office at the beginning of the movie, before anything had happened to him.
- He wasn't alone - he was with Grace. Just maintaining his cover, I spose.
The Bueller Club Theory
Cameron is hallucinating Ferris' existence. He is driving his father's car and wrecking havoc throughout the city with the girl he's fond of, all the while being chased by imaginary cartoonish authority figures.
- This can be supported amusingly well. Doesn't it seem a little convenient that on the day Ferris just happens to decide to skip school, Cameron just happens also to be at home sick? Ferris doesn't even question it - he's not even in a hurry to ring Cameron's house in case Cameron leaves for school. Why? Because the 'phone call' is Cameron's internal monologue. Why is it that we never see Cameron's parents? Answer: we do, they're just referred to as 'Ferris'' parents. 'Ferris':Cameron = Tyler Durden:Jack, and the climax of the movie is Cameron's adoption of some of Ferris' traits, while also re-asserting his primacy and dismissing Ferris, who was only ever a coping mechanism and is no longer needed - "It is possible to stop Mr Ferris Bueller, you know."
- But then how to explain Jeannie? Is she actually Cameron's sister? Or, most likely, is she Cameron's responsible side, the superego to the Ferris' id?
- And at the end, we have Cameron saying he would take responsibility at the end, and then we get the played-out conflict between his superego and his id racing home, and his superego 'wins'...but changes her mind and doesn't turn him at the last second. Does that mean Cameron didn't to take responsibility for the car when his parents did get home?
- In a deleted backstory involving the drug addict played by Charlie Sheen (named Garth Volbeck), the drug addict was a friend Ferris tried to help, but failed (and thus he turned to drugs), so he was trying to help Cameron, and stop him from turning out like Garth.
- Cameron's full name is Cameron Ferris Bueller, and he normally goes by "Ferris". He's actually fairly well-liked, but he has major impostor syndrome about that, his beautiful girlfriend, etc. He's created an idealized, happy version of himself that he thinks of as "Ferris", and he likes to imagine this version of himself as being cartoonishly popular and clever, even when facing enemies who are obsessed with him.
- Everything we saw involving Jeannie (who's entirely imaginary), and everything with Rooney after the phone call with Ferris' mother was a running daydream Cameron had while driving or waiting for his dad to come home.
- Rooney just shrugged at the apparent computer glitch and went about his day, then went home without incident. He's a blowhard, but doesn't actually have a Javert-like obsession with C. F. Bueller.
Is Sloane real or just in Cameron's mind? This idea was looked into in depthover here
- Another theory is that Ferris and Sloane are real kids that attend the school, that Cameron wishes he knew, and the entire scenario is something he day-dreamed while being sick the day of the plot.
- A twist on this theory is that Ferris is not only real, but Cameron's friend as portrayed, and the events of the day are either a fish tale that Cameron told long after the fact or an exaggeration of what really happened when he and Ferris (and Sloane) played hooky one day. The fact that Ferris seems blessed by fate (and beloved of the whole school) fits with the idea that Cameron perceives him that way rather than everything going so perfectly in reality, even while Ferris could be the sort of person who would convince his friends to go wilding in Cameron's dad's vintage car for the day.
- This is really just The Same, but More Specific Bueller Club Theory.
Not to mention:
- Constant Breaking the Fourth Wall.
- Hacking into the school computers to change his tardies.
- Wiring his intercom to a tape recorder, and using other Homemade Inventions to aid him.
- Making his principal look like an ass.
- Getting EVERYONE in Shermer to adore him.
- One-upping his twin sister.
- The day culminating with him taking a dip in the pool with his attractive girlfriend, and his best friend finally standing up to his father.
- Getting out of sticky situations in the nick of time.
Bottom line: it's a teenage escapist fantasy that never happened. Who knows: maybe he actually was sick, and he dreamed the entire thing, meaning the entirety of FBDO was seen Through the Eyes of Madness...
- Cameron could be imaginary. We never even see his parents.
- Ferris is definitely a young prototype of the Joker from The Dark Knight. They both have no rules and in spite of being rather unlikable (Ferris being a manipulative, ungrateful bastard and Joker a clearly violent and insane psychopath), have an inexplicable talent for being charismatic and getting people to follow their orders. (For the rest of this theory, see the relevant page.
- This actually makes a lot of sense. Ferris' girlfriend Sloane was Harley Quinn in Birds of Prey (2002).
- This also means that Charlie Sheen's character (named Garth Volbeck) from FBDO could be John Bender's friend and/or drug connection. Maybe Jeannie knows of Garth through her friend Claire Standish, who is dating Bender.
- And Garth might be Andy's brother.
- Doubtful; their surnames are different. Possibly cousins.
- And Garth might be Andy's brother.
- Word of God confirms that The Breakfast Club, Sixteen Candles, and Planes, Trains and Automobiles are indeed part of the same universe as Ferris.
- The reason Ed Rooney is principal is that his predecessor, Dick Vernon, got fired for reading his co-workers' private files in The Breakfast Club.
- Wasn't Rooney the truancy officer?
- The outside of the front Shermer High School in both films are different. Why? Maybe because the one from The Breakfast Club was an older school building and that in between the films, the high school was relocated to a new building. This would account for why the front of the school looks different, and the hallways in FBDO looks like it's still new, as well as why the office looks different from TBC. The older school building was on it's last days of operation prior to the relocation.
- Alternately, to fit in with the Character Development that Cameron gets, Cameron is convinced to live after his dad's Ferrari crashes, and to improve his quality of life. This means finally Calling the Old Man Out, and Cameron finally found the strength to do that.
(I stole this from http://sports.yahoo.com/mlb/blog/big_league_stew/post/Bueller-For-which-Cubs-game-did-Ferris-play-hoo?urn=mlb-318065)
- Wait, that means Ferris was like... what, 10 days from graduation? And yet the economics class is talking about the Laffer Curve. Something that is taught in the first, what, month of an economics class.
- They could be reviewing the material before the Final Exam.
- And the parade is the Van Steuben Day Parade, which happens in fall (they just happened to be filming when it happened and couldn't pass up such a chance).
- Turns out the game was in September.
- That was always my theory. And it also means Rooney won at the end:Rooney:Fifteen years from now when he looks back on the ruin his life's become...he is going to remember Edward Rooney.
- Is that really a wild mass guess or just stating canon?
- DUH.
- He just needs a car to make into a TARDIS.
- This doesn't fit with real life, at least. Virtually no odometer runs backwards when the car is in reverse, and the reality is that most teenagers don't know this so the movie situation is how it would likely play out in the real world.
- Not exactly. Anti-tamper odometers were intruduced in the mid-'70s (long after the Ferrari was made, so it shouldn't have one). These are the kind that will not run backwards. Before that, they would run backwards when driven in reverse or connected to a drill (a common shady used car dealership trick and thus why the anti-tamper device was instituted).
Ferris decided to help Cameron, and is trying to keep Cameron from ending up like Volbeck.
Garth tells this to Jeanie in the police station, and how his family life was screwed up (like how his brother ate a bunch of artificial fruit just to see what it was like to have his stomach pumped).
Rumor spread, and soon "Ferris" was being used by anyone who wanted to get out of something, but didn't want to get in trouble for it, and eventually "Ferris" became real because enough people spread rumors/started to believe in him.
How "Ferris" became a Bueller is unclear, but my guess would be that Jeannie blew off the idea of "Ferris" being real, and pointed out that, if he was actually real, and related to anyone, they'd hate him. Somehow that turned into the rumor that Ferris was Jeannie's brother, and she hated him, and the universe complied.
It's why Ferris is good at getting out of trouble/getting other people out of trouble, but he can't do everything, like get himself a car; his power is limited to avoiding getting in trouble, and getting the people he focuses on in trouble, not completely brainwashing people.
At the end, when Cameron says he wants to take credit for the Ferrari, he's not just saying he will take credit; he's swearing an oath, and Ferris cannot get Cameron out of trouble for this.
- Or, his father has a heart attack.
Seeing how the Saturday detention helped those five kids come to terms with and subvert their own screwed-up parents, Ferris realizes that Cam never got the chance to do just that, and that Cam's parental issues aren't going to be helped by conventional means. So Ferris comes up with the day off to help out his friend.
This would account for how he goes to a baseball game in June and a parade that takes place in September. The entire trip around Chicago is basically made up of places he read about and wanted to visit after he got out of school for the summer while imagining the school's reaction to him not being there, including the Economics class he was supposed to take a test on about the Hawley-Smoot Tariff Act (which he memorized back and forth for the test, which explains why the teacher is answering questions he asked), Jeanie's day at school and her attempt to "catch" him skipping. The trip to the restaurant may have been inspired by him overhearing his father complaining to his mom about the maître d’ accidentally seating people at a table that was reserved for him and his two co-workers, one of them being Abe Froman. Ferris sleeps for a full day, not getting up out of bed while being in a fever dream. And in his fever dream, he hears the footsteps of his parents coming up the stairs, which triggers the end of the story with the wrecking of the Ferrari, Cameron getting the nerve to stand up to his dad, Ferris saying goodbye to Sloane, his mad dash to get back home, encountering Rooney at the back door and his mad dash to get into bed to keep his cover from being blown. It's then his parents wake him up, checking on him, that he's back in reality again, with his concern about missing school coming up because of his "close call" in his dream with Rooney. After his parents leave the room again, Ferris nods off for a brief moment, dreaming of his final monologue, Rooney catching a lift on a bus, and his closing "it's over, go home" line before awakening again by his mom delivering soup to him.
Essentially, the whole film with the exception of Ferris being sick in bed was just an awesome fever dream with some nightmarish moments with his family, friends, and people he knows as the cast.
ADDITIONAL EDIT: I've noticed one detail that many may try to use to disprove this concept, saying that Ferris was shushing Jeanie while she was complaining about how Ferris gets to stay home but she would still have to go to school "if blood was streaming out of (her) eyes." And I do have an answer for that. If you noticed, after Jeanie comes into the room, Ferris starts calling out her name and saying, "I can't see that far," there is a point of view shot of Jeanie where we see her going in and out of focus. Now, if Ferris wasn't really sick, it wouldn't be focusing in and out like it is. That focus in and out is often used to conveyed that a character is not feeling well or drugged. When Ferris falls back, that could be when he starts drifting in and out of his fever dream, only to be wakened up by his parents to tell him that they'd check on him, and then he falls fast asleep into his fever dream after that. Another detail that makes this hypothesis possible is also in this scene itself (if Ferris wasn't dreaming, and he's clearly shushing Jeanie and looking like he's okay while doing it, why did she scream "I KNEW IT!" when she came home from school to see if Ferris was faking his sickness? She clearly knows he's not sick and faking it, and wouldn't scream "I KNEW IT!" when discovering the decoy he set up, with the only exception that she knew he wasn't in the house, which makes no sense as to why she wouldn't suspect he's not there when he's skipping).
Also, Ferris's 4th wall breaks aren't to the audience. They're to himself. And his reiteration of "Life moves pretty fast. If you don't stop and look around once in a while, you might miss it," may be his subconscious telling him to relax once in a while.
So the day Rooney breaks into the house to try to incriminate Ferris (by seeking evidence he is a truant) but is knocked unconscious by Jeannie is her actually knowing who the intruder is and getting some revenge. And later, when she helps Ferris out in the climatic scene (Rooney stopping Ferris from getting into the house), it’s not so much Jeannie deciding to look out for her brother but — with her also revealing she found his billfold on the kitchen floor from earlier — her refusal to help out someone who tried doing something despicable to her. Her comments are such that, “You’re damned lucky you’re getting away with what you did. You should be in prison!"
In the end, Grace (Rooney's secretary) comes clean; in a rare show of Edie McClurg shedding her usual cheerful demeanor, she admits that Rooney has behaved this way several times toward attractive female students, and that he has threatened Grace with more than just the loss of her job if she approaches the authorities. In an era more than 30 years before #MeToo, having Ferris busted for truancy suddenly becomes the least of Rooney's concerns ... and finally, Tom and Katie Bueller shed their usual preoccupied, clueless personas to let Rooney know they plan to have him prosecuted to the greatest extent allowed by law.
: That said, much of Jeannie's refusal to help Rooney out may have to do with her own loss of patience with Rooney, his dictator style of governing the high school, not giving a damn about the students and allowing boring teachers who have no sense of teaching (other than dry lectures that bore the students), and that it has long since been time to find a new principal who will motivate students and help them actually achieve.