The Tangerine Factor

The Tangerine Factor is the seventeenth and final episode of the first season of the CBS sitcom The Big Bang Theory. It aired on May 19th, 2008.

Plot Summary
After a bad breakup, Penny finally agrees to go out on a date with Leonard, but the two of them both develop doubts and turn to Sheldon, of all people, for advice.

Extended Plot
Howard is tutoring Sheldon in Mandarin so he can confront the Szechuan Palace, since he suspects that the restaurant is passing off Orange Chicken as Tangerine Chicken (oranges are cheaper than tangerines). Suddenly, Penny barges in, yells at someone on the street, and throws an 80 Gig White iPod Classic out the window. In her anger she explains that the person who she was yelling at, and whose iPod she threw, wrote about their sex life on his blog. Leonard goes to Penny's to find out what's happening but she furiously commands him to leave. After a small talk with the boys, Leonard musters the courage to try again, Penny's anger has transformed into depression and she explains that her boyfriend, Mike, has posted intimate details about their sex life online and her close contacts have found it. Leonard tries to comfort her, unfortunately in his attempt he convinces Penny to get back with her boyfriend. Later, Leonard is bemoaning his screw-up, when Penny comes back and has a go at him for his "stupid advice", Leonard again goes over there to ask what the problem is and Penny explains that Mike was already with a different lady that had her legs wrapped around his neck. After Penny rants about how she goes out with the wrong guys, she then proceeds to explain the type of guys she should be going out with, as her description fitted Leonard, he promptly asks Penny out, and she accepts.

Sheldon is practicing his Mandarin, when Penny asks to talk to him while he's getting his mail about advice on Leonard. After many minutes, Sheldon proposes that they draw upon Schrödinger's Cat as an analogy - after explaining it, he explains that Penny can only know for certain whether her potential relationship with Leonard is good or bad by "opening the box".

Later at the cafeteria, Leonard also seeks Sheldon's advice on dating Penny. He merely says "Schrödinger's Cat" and Leonard understands. Penny and Leonard meet the next night for their date, but Penny wants to talk first. Leonard then asks her if she ever heard of Schrödinger's cat, to which she says that she's heard far too much of it. Satisfied, he kisses her. Finally understanding what Sheldon tried to tell her, Penny proclaims that "the cat's alive" and they rush off to dinner.

Sheldon is at Szechuan Palace, arguing with the manager about the Tangerine Chicken, however his incredible flawed Mandarin leads the manager to think Sheldon is crazy, and he threatens to call the police. Sheldon doesn't realize that he's speaking the language incorrectly and thinks that their annoyed behavior and their refusal to answer his questions prove that he's right about the Tangerine Chicken. Leonard and Penny avoid entering the place and running into Sheldon in the last moment.

Quotes:

Sheldon:(Quoting incorrect Mandarin)"Show me your mucus, your mucus"

Palace Owner:"(In Mandarin) "Blow your own nose and go away"

Sheldon:"This is not tangerine bicycle"

Palace Owner:(In English) Crazy man. Call the police!"

Sheldon:"No, don't call the library, show me your mucus. Oxen are in my bed. Many, many, oxen"

Palace Owner: (Shoos him away)

Sheldon:"Oy vey!"

Critics
"I believe that this final episode is the season's best. It is not the funniest but it does engage the emotions of the viewer more than any previous effort." - The TV Critic's Review

Trivia

 * The 'little crush' that Menelaus had on Helen of Troy was enough to launch the Trojan War when Paris of Troy stole her away.
 * The Schrödinger's cat analogy recurrent through the episode is mentioned again in The Codpiece Topology, wherein Penny mentions it to a guy she goes out with, as well as in The Russian Rocket Reaction, wherein Sheldon refers to "Schrödinger's Friendship".
 * Sheldon is correct in stating that light years are a measure of distance, not time.
 * The Chinese food restaurant is not seen again until the third season's episode The Bozeman Reaction.
 * The board game that Howard, Sheldon, Leonard and Rajesh are playing in the scene where they are eating Chinese food is: Talisman: The Magical Quest Game, 4th Edition. It also appears in the previous episode, The Peanut Reaction.
 * Sheldon says, "You also made a common grammatical mistake, you said nauseous when you meant nauseated". According to Merriam Webster Usage Discussion of NAUSEOUS, such an insistence is a mistake.
 * This is the first episode where Leonard and Penny were shown to be in an relationship, though it didn't last long. They did date throughout most of the third season before breaking up in The Wheaton Recurrence, and began dating again in Season 5's The Beta Test Initiation, albeit more slowly and cautiously.
 * In the cafeteria scene with Leonard and Sheldon, Sheldon picks up a salt grinder and "shakes" salt onto his food then does the same with a pepper grinder.