South Park - Episode 0215 - Original Air Date: 28th October 1998.
This South Park episode was write only by Trey Parker.
It is near Halloween in South Park, and Cartman has skipped class but shows up at the bus stop to meet the boys when they get off the bus - wearing a goatee and acting strangely agreeable. He goes on to explain that he missed school that day because he was taking care of his mother, who has the flu. Later, when Stan and Kyle meet up with him to go buy a pumpkin, he is back to his normal obnoxious self. Throughout the episode, he continues to switch between these two personas, thoroughly confusing all involved.
Stan's aunt Flo gives him a goldfish, but Stan isn't so sure this is a good gift. When no one is looking, the fish jumps out and pulls Kenny into the fish bowl, devouring him. Stan and friends go to a strange pet store to ask about the fish, and the owner tells them about a portal that leads to a parallel world. The boys go through and evil versions of them come back to deal with the other strange animals that are causing havoc through the town.
Kenny is killed by Stan's evil fish.
South Park Spoiler Alert!
(The complete plot for this South Park Episode)
It is near Halloween in South Park, and Cartman has skipped class but shows up at the bus stop to meet the boys when they get off the bus - wearing a goatee and acting strangely agreeable. Cartman's goatee is a reference to the Star Trek: The Original Series episode of "Mirror, Mirror", whereby an evil Spock from a parellel universe wore an identical goatee. Cartman goes on to explain that he missed school that day because he was taking care of his mother, who has the flu. Later, when Stan and Kyle meet up with him to go buy a pumpkin, he is back to his normal obnoxious self (arguably even more so with his new catchphrase, "Hella"). Throughout the episode, he continues to switch between these two personas, thoroughly confusing all involved.Meanwhile, Stan arrives home, where Sharon tells him that his Aunt Flo has come to town for her "monthly visit", and gives Stan a goldfish in a bowl as a present. Stan takes an instant dislike to the fish due to its uncomfortable habit of constantly staring at him, but his mother dismisses his protests and makes him take it to his room, where it continues to stare at him most of the time and makes it hard for him to sleep. At first, the fish does not display any overtly evil tendencies, although a shirt which Stan had placed over the bowl to hide the staring fish ends up on the floor and the fish looks toward it when Stan asks it where the shirt went. Eventually, however, it starts writing messages on the inside of the bowl such as "KILL" and "Yes I Will" (the latter when Stan tells the fish, "You're not gonna get away with this.") Dead bodies also materialize next to the dresser. Stan, terrified, demands his mother remove the fish. Thinking that Stan had killed them, Sharon buries each of the bodies, while muttering to herself how Stan is handsome and a good boy and she starts slowly losing her sanity. She abducts Officer Barbrady to stop him from taking Stan away (although he showed no signs of suspicion), takes away his pants, and shackles him in the basement.
Stan, Kyle and Kenny discover that the two personalities of Cartman are in fact two separate people. Chef tells the boys that the kinder version of Cartman is from an "Evil Parallel Universe" and that Stan's fish must be from the same world, the boys ask Aunt Flo where she got the fish from and she tells them that she got it from the Ancient Indian Burial Ground Pet Store. Moments later, Aunt Flo ends up dead, and Sharon is upset that she will "no longer have her monthly visits." Randy, however, is glad he no longer has to sleep on the couch once a month. The boys decide to return the fish to its pet store, but not before it kills Kenny too, which is the first time the fish is actually seen killing anyone. Stan, Kyle and Evil-World-But-Actually-Good Cartman track down the Ancient Indian Burial Ground Pet Store, where they find the portal to the alternate universe. The store owner explains that the portal appeared after he built his shop on top of an old Indian burial ground.
After returning the fish to the owner and advising him to move his store off the burial ground, the boys leave — just as the Stan and Kyle from the evil world show up, also sporting goatees. Just as "evil" Cartman is the complete opposite of his normal self, "evil" Stan and Kyle are both the opposite of their normal selves and are thus cruel, wanting to bring their wussy "friend" Evil Cartman back so they can torment him once more. They align with Good-World-But-Actually-Evil Cartman, who is sick of his goody-two-shoes clone and the trio find Normal Stan and Kyle along with Evil-World-But-Good Cartman. In the background of the ensuing showdown, evil animals from the pet store are slaughtering people; this goes unnoticed by most of the main characters, although Sharon is now convinced that Stan's fish did really kill the people in the house.
The evil Stan and Kyle have a "gingification gun" which shoots a beam that sends things back to the alternate world. Good Stan manages to get it and sends back the two clones. He and Kyle then decide to use it on Cartman — their Cartman — so they can keep the nice one. Cartman, shocked by this, then attacks Evil Cartman and rips off his goatee. The two wrestle until Stan and Kyle do not know which is which. One Cartman says that Stan should shoot them both, so as to be sure to get rid of the "real" Cartman. Figuring this one to be the kind one, Stan fires on the other Cartman, who vanishes yelling "Screw you guys!" Unfortunately he chose wrong; Cartman — the mean one from the real world — knew that Stan and Kyle would fall for that trick and happily taunts them, to their anger.