Butters injured his eye.
In the context of South Park, Butters Stotch is a character who has experienced various mishaps throughout the series. The specific incident involving his eye could refer to an episode where he injures himself or is injured by another character. For example, in the episode “The Return of the Fellowship of the Ring to the Two Towers,” Butters gets a black eye after being hit with a weapon during the boys’ role-playing game. In another instance, Butters might hurt his eye by accident due to his naive and gullible nature, which often leads him into troublesome situations. It’s important to note that Butters’ injuries are typically played for comedic effect and are part of the show’s satirical and irreverent style.