"The Pork Chop Indeterminacy" is an episode of The Big Bang Theory that first aired on May 5, 2008. Directed by Mark Cendrowski. Teleplay by Lee Aronsohn and Bill Prady based on a story by Chuck Lorre.
Leonard notices a flier on a university bulletin board for a drug trial for a drug to help people overcome social anxiety and other psychological ailments. Maybe Raj should sign up. Raj rejects the idea.
A lot of people in the hallway are intensely interested by the tall, beautiful woman in Sheldon's office, she has him signing some papers. As they're about to leave the office, most of the onlookers disperse, leaving only Howard, Leonard and Raj. Turns out the woman is Missy Cooper (Courtney Henggeler), Sheldon's fraternal twin sister. Sheldon had to sign some papers pertaining to their late father's estate.
Howard comes on to Missy real hard, Leonard is barely better. And Raj is so frustrated by his inability to talk to Missy (he can't talk to women sober, see "The Grasshopper Experiment"), that he goes back to the bulletin board and yanks off the flier for the drug trial.
At Leonard's insistence, Missy stays at Leonard and Sheldon's apartment rather than go to a hotel. At the apartment, 4A, Howard and Leonard continue their insistent wooing of Missy. Raj shows up, excited that the new drug has given him the ability to talk to women — though with some side effects, like involuntary hand movements. Trying to court Missy, Raj is just as lacking in subtlety as Howard.
Penny offers Missy her apartment, 4B, across the hall. Missy gladly accepts the opportunity to get away from the three men hitting on her. Howard and Raj get into a physical altercation over Missy, while Leonard suggests to Sheldon that as Missy's brother and the man of the family, Sheldon needs to safeguard the Cooper pedigree that might yield another genius like Sheldon.
That backfires for Leonard, as Sheldon decrees that Leonard is just as unsuitable for Missy as Howard and Raj. But Missy rejects Sheldon's intrusion into her sex life.
Encouraged by Sheldon's reversal of his earlier decree, Howard goes to Penny's apartment to ask Missy out. Missy flatly rejects Howard, and then Leonard. When Raj shows up, Missy tells him she was hoping he'd show up. Unfortunately, Raj's medication is wearing off and he gets stuck on one word. The poor bastard walks away.
- Artistic License Biology: Referring to their gestation, Missy says she spent nine months with her legs around Sheldon's head. Sheldon ought to know but neglects to point out that fraternal twins always have separate amniotic sacs and sometimes also separate placentae. The only way that the two of them could have been in the same sac is if they were identical twins, which is obviously not the case.
- Big Brother Instinct: Sheldon's protective instinct as Missy's very slightly older brother kicks in only after Leonard appeals to Sheldon's self-interest.
- Continuity Snarl: Missy talks about a time when Sheldon built a robot arm to try and keep her from going into his room. As later shown on Young Sheldon, Sheldon and Missy shared a bedroom when they were kids. Though it should be noted that the incident took place when they were in second grade, which would have taken place before the Cooper family moved to the house in Medford as shown in Young Sheldon (as the family previously lived in Galveston and had to relocate due to George blowing the whistle on a recruiting scandal at the school he coached at), so it's possible that the twins had separate rooms in their old house. They would eventually get separate rooms in Young Sheldon, with Missy taking Georgie's old room after he drops out of high school and moves into the garage, as shown in "Pish Posh and a Secret Back Room". However, that episode strongly suggests that Missy and Sheldon had shared a bedroom all their lives.
- Groin Attack: How Missy convinces Sheldon to stop intruding in her life.
- Insufferable Genius: Missy confirms that Sheldon was one even as a child.
- One Head Taller: Sheldon's usually the tallest, but Missy also towers over all the guys (Courtney Henggeler is 5' 9").
- Ordered Apology: What Missy requires. Usually with the aforementioned Groin Attack.
- Special Odd Hand: A mild version. When Raj first takes the drug, his hand starts waving on its own.Raj: They mentioned there might be side effects.
- Test Subject for Hire: Raj signs up for a field trial for an experimental drug that boosts confidence and self-esteem, in hopes of getting over his selective mutism around women. They work and he happily converses with every girl he comes across, but he experiences side-effects including uncontrolled, repetitive hand gestures. He later tries to ask Sheldon's sister Missy out, where he's the only person she shows interest in, but predictably his medication runs out at that point and he ends up whining like a puppy.