The Pork Chop Indeterminacy
Season 1, Episode 15 - Aired May 5, 2008

Sheldon's attractive twin sister, Missy, is in town and the guys can't avoid hitting on her. As they all vie for Missy's affections, Leonard devises a plan to eliminate his rivals. Eventually, Sheldon decides he should determine who can date his sister. Meanwhile, Raj takes part in a drug trial to try overcome his selective mutism.