Just read this last night so it's pretty funny that you brought this movie up.
Mr. Rooney was the mean old Dean of Students who spent the entire movie trying to prove that Ferris was skipping school while pretending to be sick. What a mistrustful tight-ass. Why the hell does he care so much if one student takes a day off?
Let's get the obvious out of the way: this is his goddamned job. He is the Dean of Students, not the Dean of Not Giving A Damn. People are always all up the public schools system's digestive tract for not taking a more active interest in their students and that's exactly what Mr. Rooney was doing. It doesn't matter if, on a personal level, he's a dick or not -- he is literally paid with your tax money to make sure kids aren't doing exactly what Ferris did. The kid can go to a museum and drive a sports car on the weekend. During the week, he and the other kids are Rooney's responsibility so they can, you know, get an education.
And you know what? He was right all along. Ferris was skipping school. Worse yet, he lied to his parents and friends about being sick and pretty much got the whole town involved in the farce. He lied, he stole, and he caused millions in property damage by destroying Cameron's dad's beautiful car. That's not adorable, that's just being an egocentric crock. It wouldn't have been a satisfying movie ending to see Rooney expose Bueller for his douchebaggery, but it would have been by far the more just outcome. What happens instead is that Rooney loses his wallet and almost has his nipples ripped off by a Rottweiler.
And we're asked to sit back and say, "serves him right for caring about the future of our country!"
You know, this has always bothered me about this movie, especially the stuff about Ferris being a douche. Which he is? I didn't like him. He's that drunk clown at the party that acts like a Fake Sugar Dick (WARNING, NOT THE REAL SUGAR DICK!) and yet no one can see through him but you (think Barack Obama).
A thing that always bugged me in a movie--a good friend pointed this out recently--is in Empire Strikes Back ...
Han, Leia, and company are being chased by the empire in the Falcon.
Meanwhile, Luke is receiving his Jedi training on Dagobah.
The movie cuts back and forth between the two, and the two storylines converge at Lando's cloud city AT THE SAME TIME.
So ...
Either the Empire was chasing Han Solo and Princess Leia for months and months and months, or ...
... it only takes a few hours to complete Jedi training.