South Park (1997)

S3E7 Cat Orgy

Shelly Marsh is watching over Cartman when she decides to invite her boyfriend over. He, in turn, brings along his band. Cartman feels the need to show that Shelly has broken the rules. At the same time, Cartman's cat, in heat, is on the prowl for company and gathers all the neighborhood cats back to the vacant Cartman home for a wild gathering.