'[Sheldon reveals that Leonard betrayed both Raj and Howard's trust by sleeping with Raj's sister, Priya]
Raj: [getting up to leave] I don't believe it. This is a terrible betrayal of my trust.
Leonard: No, no - would it help if I told you that I offered her my heart and that she kind of stomped on it?
Raj: ... How hard did she stomp?
Leonard: Very hard!
Raj: Okay, I'm good. [Sits back down]
Howard: Raj, I just want to say I'd never betray your trust. Unlike Leonard, I respect you.
Leonard: Really? Was it out of respect that you didn't tell Raj about the time you dropped his iPhone in a urinal?
Raj: [horrified] DUDE, I PUT THAT THING ON MY FACE!
Sheldon: I think a more amusing violation of Raj's trust is when Howard convinced him that foreigners give presents to Americans on Thanksgiving.
Howard: Hey, I didn't see you giving back your Snoopy Snow-cone maker!
Raj: That was all a lie!? This year's gifts are already wrapped!
Howard: And as long as we're talking about betraying our friends, how about the month Sheldon spent grinding up insects and mixing them into Leonard's food?
[Leonard looks horrified]
Sheldon: Well, excuse me! That was not a betrayal. That was an experiment to determine at what concentration food starts tasting "mothy."
Leonard: YOU PUT MOTHS IN MY FOOD!?!?!?
Sheldon: For science.
'Raj": I can't believe you kissed my sister with moth mouth!
Leonard: Well, I can't believe you used Sheldon's toothbrush!
Sheldon: YOU USED MY TOOTHBRUSH!?!?!?!?!??!!?!??!
Raj: Not the brush part, just the little rubber thing to pick food from my teeth and massage my gums.
[Sheldon starts blinking furiously]

Amy: Are we nervous, Dr. Cooper?
Sheldon: No. What you see is a man trembling with confidence... Does the locus coeruleus usually bleed that much?
Amy: No, but your thumb does.
Sheldon: Oh dear! [faints]
Amy: Yeah, YOU'RE a biologist.

Amy: Before I met you, I was a mousy wallflower. But look at me now. I'm like some kind of downtown hipster party girl! With a posse, a boyfriend, and a new lace bra that hooks in the front of all things!

Amy: Hang on, Doctor C. What's vexillology?
Sheldon: Vexillology is the study of flags.
Amy: Cool. I think I just learned something!
Sheldon: Did you have fun doing it?
Amy: I'll say!
[Leonard walks into his apartment after his date with Penny]

Amy: I can stop pretending that some beautiful girl and her cute-in-the-right-light friend want to hang out with me.
Bernadette: Amy, we're really sorry.
Penny: Yeah, we feel awful.
Amy: Don't. I'm be okay. You're not the first girls I thought were friends with me who ended up shunning me. It's like elementary school, junior high, high school, undergrad, grad school, and that semester abroad in Norway all over again.
Penny: Oh, come on, Amy.
Amy: You don't get it. [holding a piece of brain] Look at this brain.
Penny: [getting sick] I don't really want to.
Amy: This is us. Bernadette, you're the analytical, scientific left hemisphere. Penny, you're the creative, spontaneous right hemisphere. And where's Amy? [Lays the brain on a tray, picks up a tumor with a knife and holds it up] She's right here--the sad little tumor no one wants to go dress shopping with.
Bernadette: Amy, you're not a tumor. Penny, tell her she's not a tumor.
[Penny is throwing up in a garbage can]

Amy: I don't understand. What difference does it make if Leonard goes to Wil Wheaton's party?
Penny: Wil Wheaton is Sheldon's mortal enemy.
Amy: Mortal enemy? Sheldon, I know you're a bit of a left-handed monkey wrench, but you really have a mortal enemy?
Sheldon: In fact, I have 61 of them. Would you like to see the list?

Amy: I find the notion of romantic love to be an unnecessary cultural construct that has no value to human relationships.
Sheldon: Amy Farrah Fowler, that's the most pragmatic thing anyone has ever said to me.
Amy: I trust this clarification allows us to return to boy-slash-friend-slash-girl-slash-friend status?
Sheldon: Of course. Would you like to join me for Chinese food?
Amy: Sheldon, please, you're suffocating me.

Amy: Jewelry? Seriously? Sheldon, you are the most shallow, self-centered person I have ever met. Do you really think that another transparent manip...[pulls out of the bag...] Ohhhhhh, it's a tiara! A tiara! I have a tiara! [Rushes to Penny] Put it on me. Put it on me. Put it on me. Put it on me. Put it on me. Put it on me. Put it on me.
Penny: [placing it on Amy's head] You look beautiful!
Amy: OF COURSE I DO! I'M A PRINCESS AND THIS IS MY TIARA!
[She excitedly kisses Sheldon]
Sheldon: [to Penny] You're right, the tiara was too much.

Amy: Penny's friend, Zack, stopped by and said "hello" and I said "hoo!"
Sheldon: Hoo?
Amy: Zack.
Sheldon: Then why did you ask?
Amy: Ask what?
Sheldon: Who?
Amy: Zack.
Sheldon: Alright, let's start over. What did you say when Zack walked in?
Amy: Hoo!
Sheldon: Zack.
Amy: Why do you keep saying 'Zack'?
Sheldon: Because you keep saying 'Who'.
Amy: I'm not saying 'hoo' now. I said 'hoo' last night.
Sheldon: And the answer was Zack, correct?
Amy: There was no question; I simply said "Hoo!"
Sheldon: [short pause] All right. I think I have enough to go on.

Amy: Sheldon, what are you doing here?
Sheldon: The thought of you sitting in a darkened theatre with a character like Stuart is repellant. No offense Stuart!
Stuart: None taken. Though, repellant, is kind of, kind of a strong word.
Amy: Um... sorry this causes you discomfort but based on the currently established parameters of our relationship, I can put myself in any repellant situation I want.
Stuart: Um...again...
Sheldon: Stuart please, you're being rude.
Amy: Anything else?
Sheldon: I believe, I would like to alter the paradigm of our relationship.
Amy: I'm listening.
Sheldon: With the understanding that nothing changes whatsoever, physical or otherwise. I would not object to us no longer characterizing you as not my girlfriend.
Amy: Interesting... Now try it without the quadruple negative.
Sheldon: You're being impossible!
Amy: Hi, Stuart.
Sheldon: Fine! Amy, will you be my girlfriend?
Amy: Yes!
Sheldon: Alright, that's enough about it. Sorry to interrupt. You two enjoy your date!

Amy: So anyway to make a long story short, turns out I have an unusually firm cervix.
Penny: You know Amy, when we say girl talk that just doesn't have to be about our lady parts.
Amy: [That's a] Shame, cause I have a real zinger about my tilted uterus.
Penny: So what do you girls wanna do tonight? Should we go to the club or to the movies?
Bernadette: Or we could just stay here?
Amy: Yes, and continue to bond. I have a feeling that after tonight, one of you will become my best friend forever, or BFF if you prefer - which I don't.

Amy: Well, the Internet suggests that another popular slumber party activity is experimentation with lesbianism.
Bernadette: Where exactly on the Internet have you been looking?

Bernadette: So we just sit and stare at a screen and wait for something to happen?
Howard: I did it with you when we rented The Notebook.

Dimitri: [in Russian] Mission Control, say again, how fast is it leaking?
Howard: Leaking? What's leaking?
Dimitri: Fuel. Shh.
Mission Control: [in Russian] Not bad. We feel okay to go.
Dimitri: [in Russian] Okay, thanks Mission Control.
Howard: There's fuel leaking and we're still going to go?
Mike: Don't lose your Froot Loops, Froot Loops.
Dimitri: This happens a lot. Nine times out of ten, no problem.
Howard: What happens on the tenth time?
Dimitri: Problem.

Dr. Beverly Hofstadter: [after hugging Leonard] I'm getting a warm feeling across my chest.
Penny: That'll be the Del Taco.
Sheldon: Why is Leonard softly banging his head on his bedroom door?
Dr. Beverly Hofstadter: Speaking of warm feelings, come here! (kisses Sheldon square on the lips) Nah, I'd rather have the busboy.