Penny: Well, Sheldon you are his friend. Friends give each other presents.
Sheldon: I accept your premise; I reject your conclusion.
Wolowitz [whispers]: Try telling him it's a non-optional social convention.
Penny: What?
Wolowitz: Just do it.
Penny: It's a non-optional social convention.
Sheldon: Ahh, fair enough.
Wolowitz: He came with a manual

Penny [on phone]: How about this, you keep him there a little longer, and when you get to the party, I'll point out which of my friends are easy.
Wolowitz: ... Don't toy with me, woman.
Penny: I got a hot former fat girl with no self-esteem, I got a girl who punishes her father by sleeping around, and an alcoholic who's two tequila shots away from letting you wear her like a hat.
Wolowitz: Thy will be done

Raj: Missy, do you enjoy pajamas?
Missy: I guess.
Raj: We Indians invented them. You're welcome.
Wolowitz: Yeah, well, my people invented circumcision

Wolowitz: Okay, you two have to back off.
Raj: Why should I back off? You back off, dude.
Leonard: Excuse me, this is my apartment, and she's my roommate's sister.
Howard: So what? You've already got Penny.
Leonard: How do I have Penny? In what universe do I have Penny?
Wolowitz: So, I can have Penny?
Leonard: Hell, no!

I'd kill my rabbi with a pork chop to be with your sister

Penny [to Leonard]: Look, you are a great guy, and it is the things you love that make you who you are.
Wolowitz: I guess that makes me large breasts

Sheldon: I propose we add "pants must be worn at all times in the time machine"
Leonard: Seconded.
Wolowitz: I was gonna put down a towel

Leonard: The elevator's been broken for two years.
Sheldon: I've been meaning to ask you. Do you think we should make a call about that?
Wolowitz: Not necessary. I have a Masters in Engineering. I remotely repair satellites in a regular basis. I troubleshoot space shuttle payloads. When the Mars Rover started pulling to the left I performed a front-end alignment from 62 million miles away. [pushes the button...] No, that baby's broken

Leonard: Come on, guys, push!
Howard: If I push any harder I'm gonna give birth to my colon.
Raj: I can't feel my fingers. Hurry up!
Sheldon: It's the same amount of work no matter how fast you go—basic physics.
Raj: Sheldon, if my fingers ever work again, I've got a job for the middle one

Raj: Too bad, I called dibs.
Wolowitz: You can't just call dibs.
Raj: I can, and I did. Look up "dibs" in Wikipedia.
Sheldon: Dibs does not apply in a bidding war

Wolowitz: Don't you think I should answer the engineering question? I am an engineer.
Sheldon: By that logic I should answer all the anthropology questions because I'm a mammal

[Raj whispers in Wolowitz's ear]
Penny: What did he say?
Wolowitz: He compared Sheldon to a disposable feminine cleansing product one might use on a summer's eve.
Penny: Yeah, and the bag it came in

TBBT Quotes

Sheldon: Why do you have the Chinese character for "soup" tattooed on your right buttock?
Penny: It's not "soup," it's "courage."
Sheldon: No it isn't. But I suppose it does take courage to demonstrate that kind of commitment to soup.
Penny: How'd you see it? You said you wouldn't look.
Sheldon: Sorry. As I told you, the hero always peeks.

Sheldon: Nothing more fun than a paradigm shifting evening of science.
Penny: (to Leonard) And you thought it was soaping me up in the shower.