Penny: Sheldon, could I ask you a question?
Sheldon: I would prefer that you not, but I wouldn't go so far as to forbid it.

Sheldon: I wouldn't tell you the secret. Sssh!
Leonard: What secret? Tell me the secret.
Sheldon: Mom smokes in the car. Jesus is okay with it, but we can't tell dad.
Leonard: Not that secret, the other secret.
Sheldon: I'm Batman! Ssssh!

Penny: I meant has he ever been involved with someone who wasn't a brainiac?
Sheldon: Oh! Well, a few years ago, he did go out with a woman who had a Ph.D in French Literature.
Penny: How is that not a brainiac?
Sheldon: Well, for one thing she was French.

Penny: Look, just forget I told you about me not graduating from community college, okay?
Sheldon: Forget? You want me to forget? This mind does not forget. I haven't forgotten a thing since the day my mother stopped breast-feeding me. It was a drizzly Tuesday.

Raj: I hate trains.
Sheldon: Oh, don't be silly. You love trains.

Leonard: Penny thinks I'm too smart for her. That's ridiculous!
Sheldon: I know! Most of your work is extremely derivative. And don't worry, that's not a secret.

Sheldon: I'm baaaaaaaaaaaaaaaack.

Sheldon: (In Mandarin) Show me your mucus. Your mucus!
Chen: (Mandarin) Blow your own nose and go away!
Sheldon: (Mandarin) This is not a tangerine bicycle. Show me your mucus!
Chen: Crazy man. Call the police.
Sheldon: (Mandarin) No, don't call the library. Show me your mucus.

Sheldon: (In Mandarin) Many oxen are in my bed! Many, many oxen!
*Chen flings his hands at Sheldon*
Sheldon: (Mandarin) Oy Vey.

Sheldon: (Speaking Chinese to Leonard).
Howard: You just called Leonard a syphillitic donkey.
Sheldon: My apologies, Leonard. I'm only as good as my teacher.

Sheldon: Howard, I'm gonna need another mandarin lesson, I obviously didn't make my point with those people.
Howard: For God's sake, Sheldon, if you don't like the tangerine chicken, don't order the tangerine chicken.
Sheldon: I like tangerine chicken, I'm just not getting tangerine chicken.

Sheldon: (Practising speaking Mandarin) Show me your citrus peels.
Penny: Sheldon?
*Sheldon freaks out in Chinese.*
Penny: I'm sorry. Look, do you have a second?
Sheldon: A second what? Pair of underwear?

Penny: Leonard might be home, can we talk in my apartment?
Sheldon: We're not done?
Penny: No!
Sheldon: Eh, why not? We're already through the looking glass anyway.

Penny: What I'm saying is, Leonard might be different in a good way. And obviously, my usual choices have not worked out so well.
Sheldon: Your last choice worked out for Koothrappali. He got a free iPod.

Sheldon: (Mandarin) Long live concrete? Thank you.