Leonard: That's not helpful.
Howard: Then I won't say I'd like to cover three quarters of her surface area.

Sheldon: Would you pass the mustard.
Leonard: Sure. Hey, you wanna hear a fun fact about mustard?
Sheldon: Is it that the glucosinolates that give mustard its flavor were evolved by the cabbage family as a defense against caterpillars?
Leonard: Yeah.
Sheldon: Well, that was fun. Good for you, Leonard.

Leonard: This was Feynman's van? This is so cool.
Raj: Yeah, nothing's been changed since he drove it.
Howard: Bet he picked up a lot of cute grad students in this bad boy.
Sheldon: And talked about physics with them.

Raj: Hey, look! The lug nut's off.

Penny: Hey, we're going to dinner. You want to come?
Sheldon: Oh, I wish I could, but I realized I've become too emotionally vulnerable, so, like an operating system, I'm restoring my life to the last stable version, which was in 2003, the day before I met Leonard.
Leonard: You heard him, no.

Leonard: Come on, Barry, there's a Swedish team trying to run our experiment before us.
Can't you spare any?
Barry Kripke: Be honest, if the shoe was on the other foot, would you do this for me?
Leonard: Yes.
Sheldon: No chance.
Leonard: What are you doing?
Sheldon: He said be honest, so I was honest. Didn't your mother tell you? It's the best policy.

Raj: Why do you need Kripke? Why don't you just go to Party City for helium?
Leonard: We'd have to go to every Party City in California.
Howard: Sounds like you on Cinco de Mayo.
Raj: Hey, people were still talking about that party on siete de Mayo.

Bernadette: Hey, I thought you were gonna be out late?
Howard: If you wanted me to stay out later, you should've given me more spending money.

Sheldon: Wait, hold on, hold on. How do we know that you're not gonna take the money and drive away?
Leonard: What ya doing, Skippy?
Sheldon: Exactly what 1970s television crime dramas have taught us.
You give us the helium first.
Dealer: Oh, how do I know you're not gonna drive away without paying me?
Sheldon: Guess I'm not the only one who watches '70s television crime dramas.

Dealer: Huh. All these years, I've been using stalemate, when I really mean impasse. I feel foolish.
Leonard: I don't think it matters if this is a stalemate or an impasse or a Mexican standoff. What are we gonna do here?
Dealer: Oh, whoa, whoa, how can it be a Mexican standoff? Everybody knows you need three sides for that.
Sheldon: Not necessarily. Uh, many argue the essence of a Mexican standoff is that no one can walk away from the conflict without incurring harm.
Dealer: Hmm, I don't follow.
Sheldon: Let me give you an example. Earlier today, I decoded the headers on your e-mail, and I know that your name is Kenneth Fitzgerald.
From that, I figured out where you live and where you work.
Now, to make this a Mexican standoff, I would say something like, uh, "You give us the helium or I'll turn you in to the authorities."
Dealer: Is that a threat?
Sheldon: Yeah, exactly. See, you're getting it.
Dealer: Yeah, well, I know where you work, all right? And if you mess with me, I'll report you, then I'll pound your asses into the ground.
Sheldon: Perfect! Now we really are in a Mexican stand-off.

Bernadette: Ew, check out his tiny teeth. He looks like a man-dolphin.
Penny: Wait, if he's good in bed, she can throw him a fish.
Howard: (high-pitched) I love you, Amy. (dolphin sounds)

Sheldon: What if the helium dealer rats us out? What if Kripke asks where we got it? What if the university checks my family tree and finds out I don't have an Uncle Harvey?
Leonard: The dealer doesn't care, Kripke has no authority over us, and you being related to a metal container would explain a lot.

Amy: It's going fine. It's mostly just been meeting people for coffee.
Raj: Wha?!
I thought we were all- Never mind.

Leonard: Can you give us a minute?
Barry Kripke: Take your time. I'll walk out backwards for dramatic effect.

Leonard: How long have you known Adam?
Wil Wheaton: A few years.
Leonard: Mm-hmm. And what are you getting him back for?