CBS

Season 1: Episode 15 - The Pork Chop Indeterminacy

The Pork Chop Indeterminacy: Sheldon's twin sister comes into town, and she is a complete knockout. Leonard, Wolowitz, and Koothrappali go crazy for her and compete for her attention. When Leonard devises a plan to eliminate his rivals, it backfires when Sheldon declares he will decide whom his sister dates.