Original air date: 4/10/2002
Stan, Cartman and Kyle kick Butters out of their group of friends due to them thinking that he's too lame to fit in with them. Butters, unhappy with this betrayal, turns into a supervillain named "Professor Chaos" and causes mayhem throughout South Park. Meanwhile, the boys try to find a new fourth friend to fill Kenny's spot.
"Professor Chaos" contains examples of:
- Breaking the Fourth Wall: Cartman when he describes DogPoo as a "prop".
- Call-Back: When Butters is sitting upset in his dark room, he enlists things he's done for the boys throughout their short-lived friendship, which include putting balls on his chin to star on The Maury Povich Show and buying tampons for Stan's sister Shelley.
- Face–Heel Turn: Butters becomes a super villain that attempts to bring the world to destruction after the boys drop him as the fourth friend.
- Firing Day: Butters getting kicked out of the friend group isn't technically a firing, but it's certainly staged like one.
- Harmless Villain: Butters' evil schemes are either too small-scale to be considered any kind of a threat, or way too large for a single boy to actually do.
- Jerkass Has a Point: Invoked between Kyle and Cartman:Kyle: What about Token?
Cartman: Token's a smartass.
Kyle: So? You're a smartass.
Cartman: Yeah but do we need another one?
Kyle: Good point. - Living Prop: How Cartman describes DogPoo since he never gets to say or do anything despite hanging with the class for years (although he does speak for the very first time in this episode).DogPoo: I think I deserve to take Kenny's place the most, because, I've been hanging around these guys for like five years and I never get to say or do anything.
Cartman: Yeah, I've seen that kid in class, but he never does anything. He's more like a prop. - Oh, and X Dies: The narration at the end of the episode offhandedly mentions Ms. Choksondik will die in the next one.
- Poke the Poodle: Most of Professor Chaos' attempts to bring the world to destruction involve switching soup orders at Bennigan's, stealing the teacher's eraser, and drowning the entire world with a hose. The last plan fails, to say the least.
- The Shadow Knows: As Butters monologues about his loneliness and how he has no real friends in the world, his shadow morphs into that of a sad-looking person.
- To Be Continued... Right Now: The episode sets up three cliffhangers which initially seem like they supposed to be expanded upon in the following episode, such as whether Professor Chaos' plans will succeed, the boys' new fourth friend, and which South Park resident will be killed off and never seen again. But at the end of the episode a narrator sums up these questions, and then straight up answers them with: No, Tweek, Ms. Choksondik.
- Too Dumb to Fool: Butters, as Professor Chaos, tries to scare the world by pretending to flood the entire planet with his garden hose, only for everyone to excitedly grab their swimgear instead.
- Yank the Dog's Chain: Pip, the most hated kid in school and a frequent target of bullying for the boys, actually manages to pass the first two waves of auditions to be the fourth friend in their group. Then he asks for crumpets and tea at a baseball game, and Cartman promptly tells him to get the fudge out, disqualifying him on the spot.
