Kyle and Stan are building a snowman with their new best friend Tweek. Cartman arrives showing them an ad for "Sea People" and convinces them to each contribute $4 a piece so they can place their order and have them tomorrow. Butters (as Professor Chaos) and General Disarray start to launch "Evil Plot 4-B", which is to blot out the sun with an 80 foot high by 50 foot wide giant shade. General Disarray informs him that they already did that on The Simpsons. Professor Chaos looks for another plan. Cartman dreams about having adventure with his "Sea People." The "Sea People" have arrived and Cartman prepares his friends to help welcome them. Stan identifies the "Sea People" for what they really are brine shrimp. Cartman is discouraged, his dreams of the "Sea People" taking him away from reality have been destroyed, and he wants them thrown away. Kyle suggests that they put them in their teacher's coffee the next morning, which they agree to do. Cut to the next morning when the boys and others are watching Ms. Choksondik's body being loaded into an ambulance. Cartman tells the other boys they must keep a strict vow of silence on the matter, to which Tweek exclaims "Jesus Christ we killed her!" At the home of General Disarray, Professor Chaos arrives with the results of his latest scheme. He has removed the head from the statue in the town's square. The local news coverage reminds him that this same event occurred in a classic episode of the The Simpsons. Everyone in town is delighted at the prank and prefers to leave it headless so that they can always be reminded of this classic show. Professor Chaos is bummed out. Meanwhile, the boys are watching "Terrence & Philip" and are pretending like nothing has happened. When they switch over to the news they see a report that says that the cause of death for Diane Choksondik has not yet been found, but a quantity of "Sea Men" was found in her stomach. Tweek wants nothing to do with the others, but they suggest that he, as their new best friend, might have to take the fall.
The boys go to see Chef for some advice and he has none to offer. They decide that they must break into the morgue and retrieve their "Sea Men" from Ms. Choksondik's body. Professor Chaos lies out "Plan #123-D" (monorail) for General Disarray, who informs him "The Simpsons already did it in episode 204(sic)". [See note 1 below.] The Simpsons have also already done his plans #124-A (web site gossip) and #129-E (buried angel) as well. At the hospital, the boys search for "Sea Men" in Ms. Choksondik's body. When the morgue attendants return, the boys hide. With nowhere else to go, Cartman hides himself in Ms. Choksondik's body. When the coast is clear, the boys escape, but Cartman remains behind to gather the sample. Professor Chaos is informed that The Simpsons have already done plans #127-C (soccer riot) and #125-E (shaken beer can). Discouraged, Professor Chaos decides he might just run away and join the circus, until he is informed "The Simpsons did it." [See note 2 below.] Cartman has Ms. Choksondik's semen sample, which he returns to the "Sea People" tank. Chef arrives with tickets to get them out of town. They tell him that he doesn't need to worry any longer; they've retrieved the "Sea Men." Confused, he has them tell their story from the beginning. Now that Chef understands what has really happened, he tells them there is nothing to worry about; Ms. Choksondik couldn't have died from the brine shrimp. Chef and the other boys leave Cartman in his bedroom, where he goes to sleep with no worries; but he soon may have something to worry about as the sperm in the semen sample that he put into his "Sea People" tank have joined with the brine shrimp.
At the bus stop the next morning Cartman gets the boys to come to his place to see what has happened. It seems per Cartman's "Final Theory of Composite Dynamics" that the "Sea People + Sea Men" have joined together to create a "Sea Ciety," to the point where they have built buildings, etc. Cartman wants to where they can take this, so he needs a bigger tank, more "Sea People" (5 gallons worth) and 10 gallons of "Sea Men," which he will go out on the town and collect himself. Having watched all 132 episodes (sic) of the The Simpsons [See note 3 below.], Professor Chaos is hit upon a scheme that they haven't already done, that is to replace the contents of a cherry with "yukky, sticky mayonnaise." General Disarray comments that The Simpsons' scheme would have been more clever. When they are ready to leave to execute this evil scheme an ad comes on for tonight's episode of The Simpsons in which Bart is going to replace the contents of a chocolate covered cherry with mayonnaise. [See note 4 below.] At South Park's Sperm Bank Cartman negotiates to get all the semen they can give him. Professor Chaos is seeing The Simpsons in everyone and everywhere he goes. At Cartman's home all the elements come together to allow them to see what kind of "Sea Ciety" they can create with the bigger tank.
The following morning, Cartman awakes to find that the "Sea People" have evolved even further. The "Sea People" are worshipping his as their god. Everyone is invited over to Cartman's house to see this new "Sea Ciety." Butters is there, but is still seeing The Simpsons in everyone and everything. In fact he even realizes that Cartman's civilization was already done as a story on the The Simpsons. To which the boys reply "so;" after all The Simpsons have been on the air for over 13 years and they have already done everything. Chef adds that the particular part of The Simpsons was actually taken from an episode of The Twilight Zone. With all this new information, Butters is ready to wreak chaos once again. Meanwhile in the "Sea Ciety" a statue of Tweek is created and the two disparate parts of the "Sea Ciety" go to war with each another and blow themselves up.