The Porkchop Indeterminacy

"The Porkchop Indeterminacy" is the fifteenth episode of the first season of the   The Big Bang Theory. This episode first aired on May 5, 2008.

Summary
Sheldon's attractive twin sister, Missy, is in town and the guys can't resist hitting on her, while Raj takes part in a drug trial to suppress his.

Extended Plot
Leonard and Raj notice a flyer for a drug trial that can help with Raj's selective mutism. They soon bump into Howard who was peeping into Sheldon's Office. Howard explained there was a very attractive woman in Sheldon's office. Soon, Sheldon and the woman come out and the gang acts friendly with Sheldon in an attempt to befriend the woman. She first tells the guys that she spent nine months with her legs wrapped around his neck, which confuses Leonard. Sheldon soon introduces her as Missy, his fraternal twin sister. Missy talks to the gang and after Raj's selective mutism becomes a hindering factor in befriending her, he takes up the flyer for the drug trial. Missy explains she is in town because her friend is getting married at, and since she doesn't have anywhere to stay, Leonard suggests she stay at their apartment. After some convincing, Sheldon agrees.

Back at the apartment, Leonard, Howard, and Raj, who is now on a test drug which has suppressed his selective mutism, manages to creep Missy out by hitting on her excessively. Penny rescues her by offering to get her nails done and avoid the boys. Leonard gets sneaky and tells Sheldon he has to protect Missy's integrity and only let someone suitable fertilize it in order to produce an individual as remarkable as Sheldon himself. But this ultimately backfires as Sheldon deems Howard and Raj unworthy and rules Leonard out because of his lactose intolerance. Leonard objects to which Sheldon replies that he can sleep with his sister if he can eat a slice of cheese without having gas. Missy witnesses this exchange and orders Sheldon into his bedroom. After she talks to him privately about who determines who she sleeps with, Sheldon announces that Missy can date whoever she likes (but this is because she squeezed his testicles when he still didn't get the message). Leonard, Howard, and Raj decide to hit on her more humanely.

Because Leonard wins at Wii-Boxing, he also wins the right to ask Missy out first, but she turns him down, something they didn't anticipate. Next up, Howard gives it a shot and also fails. Lastly, Raj calls by and gives it a go, Missy seems to have developed a liking for Raj but his medication wears off and he is unable to ask her out. Finally, Sheldon sees Missy off and is distressed that she tells every one he is a rocket scientist, believing it to be beneath him.

Quotes
Sheldon's hot twin sister, Missy, is in town for a wedding

Leonard: If the wedding's not until tomorrow, why don't you stay with us tonight?

Missy: Oh, I don't think so. Shelly doesn't like company. Even as a little boy, he'd send his imaginary friends home at the end of the day.

Sheldon: They were not "friends". They were imaginary colleagues.

Penny: So, Sheldon's sister is pretty cute.

Leonard: I wasn't staring!

Penny: I didn't say you were; I just said she was cute.

Leonard: Oh! Uh, maybe... if you like women who are tall... and perfect.

Penny: Sheldon, why are you ignoring your sister?

Sheldon: I'm not ignoring my sister. I'm ignoring all of you.

(Leonard wants to sleep with Missy, but Sheldon doesn't let him.)

Sheldon: Here. Eat this cheese without farting and you can sleep with my sister.

(Missy is leaving and Sheldon is saying goodbye to her.)

Sheldon: OK, well, it was pleasant seeing you, other than that business with my testicles. (Puts his hand out for her to shake.)

Missy: Come on, Shelly. (Gives him a hug, which Sheldon does as well.)

Missy: I want you to know I'm very proud of you.

Sheldon: Really?

Missy: Yep. I'm always bragging to my friends about my brother, the Rocket Scientist.

(Sheldon looks in disbelief.)

Sheldon: You tell people I'm a Rocket Scientist?!

Missy: Well, yeah.

Sheldon: I'm a theoretical physicist.

Missy: What's the difference?

Sheldon: What's the difference?!

Missy: Goodbye, Shelly.

Sheldon: My God! Why don't you just tell them I'm a toll taker at the Golden Gate Bridge?! Rocket Scientist, how humiliating!

Leonard: Sheldon, are you going to introduce us?

Sheldon: Oh, alright, this is Missy, Missy this is Leonard and Rajesh and you’ve already met Howard.

Missy: It’s nice to meet you.

Leonard: You too, swell, also.

Howard: Yeah.

Leonard: So, how do you two know each other.

Missy: Oh, he once spent nine months with my legs wrapped around his head.

Leonard: Excuse me?

Sheldon: She’s my twin sister, she thinks she’s funny but frankly I’ve never been able to see it.

Missy: It’s because you have no measurable sense of humor, Shelly.

Sheldon: How exactly would one measure a sense of humor? A humormometer?

Missy: Okay, Shelly, sit down. Now I've lived my whole life dealing with the fact that my twin brother is, as Mom puts it, one of God’s special little people.

Sheldon: I always thought I was more like a cuckoo bird. You know, a superior creature whose egg is placed in the nest of ordinary birds. Of course the newly hatched cuckoo eats all the food, leaving the ordinary siblings to starve to death. Luckily for you, that’s where the metaphor ended.

Missy: I thought it ended at cuckoo. Now you listen to me, if you want to start acting like a brother who cares about me, then terrific. Bring it on. But you try one time to tell me who I should be sleeping with, and you and I are going to go round and round the way we did when we were little. Remember? (Sheldon hurriedly crosses his legs.)

Critics

 * "The humor is pretty solid throughout and should entertain, even though there is a greater opportunity for character development wasted." - The TV Critic's Review
 * IMDb user reviews

Trivia

 * This is the second time that Raj is able to talk to a girl. Previously, it took a large dose of, while this time he using an experimental drug.
 * Missy calls Sheldon by his nickname, "Shelly", just like their mother.
 * The original title for this episode, still used internationally in English-speaking territories, is "The Indeterminacy".
 * Leonard says, "We don’t entertain much." This is similar to his statement in the "Pilot", "We don’t have a lot of company over." Yet, Sheldon made his resentment for such clear in that episode. It may be that he was implying that they (the four guys) do not entertain much (outside of their social circle) and thus have little idea how to be good hosts.
 * In the pilot, Sheldon tells Leonard that his sister is a hostess at.
 * This is the first and only, to date apperance of Missy.