Spoilers for some characters' stories
Cartman
-His final plan to go unconscious to avoid doing his history report by being dropped into a pool with a toaster thrown in (among other things) in the episode 'I'm a Little Bit Country'
-When the cops tell him all of his felonies and mention how long in Casa Bonita then replying it was 'totally' worth it
-The ending of Scott Tenorman must die
-The ending of 201 when he cries about being half Jew
Kyle
-Organizing the pedophiles to attend Cartman's dateline interview in Les Petit Tourettes
-Telling Cartman frankly that he hates him (I can't remember this episode off the top of my head, Cartman is asking him for a favor or something and Kyle just responds with, I hate you or Because I hate you)
Butters
-Beating up villains then returning to the bus with Cartman saying "Teacher, my partner is back on the bus" at the end of Super Fun Time
-Killing everyone at the end of 'You got F***** in the A'
Kenny
-Throwing the ninja star into Butters' eye in 'Fun Times with Weapons'
Stan Marsh
End of scientology episode when he yells 'Fine! Sue Me'
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Notyou