This is the beginning of a three-episode story arc in which each episode reveals what Eric, Stan, and Kyle are up to while their parents attend a meteor shower party. Eric's mother hires Stan's older sister Shelly to babysit. Shelly breaks the rules and invites her boyfriend over. They break up, and Eric helps Shelly get back at him. When they return to the Cartman home, they discover that their "in-heat" feline has invited over some friends. This typically irreverent episode of South Park, "Cat Orgy," first aired July 14, 1999, on Comedy Central.