South Park: Season 3, Episode 7

3 - 7: Cat Orgy

During a big meteor shower, all the parents in town go to a party, so Shelley baby-sits Cartman. Shelley won't take any crap from him, plus, she invites her much-older boyfriend over, which really infuriates Cartman. "Mr. Kitty" is in heat, and goes off in search of a good time.