Leonard: Wait, wait, wait. You had surgery?
Beverly Hofstadter: Yes, and Sheldon sent me flowers.
Leonard: I heard that.
Beverly Hofstadter: Then what was all that "wait, wait, wait" about?

Ira Flatow: Thanks for being with us today, Dr. Cooper.
Sheldon: My pleasure, Ira.
Ira Flatow: Now, let's talk about magnetic monopoles. Can you explain to our audience just what a monopole is?
Sheldon: Of course. First, consider an ordinary magnet, which has, as even the most uneducated (voice becoming high-pitched) in your audience must know, two poles (clears throat) a north and south pole. If you cut that in half, you have 2 smaller magnets each with it's own north and south pole.
Ira Flatow: Dr. Cooper, I think there might be something wrong with our connection.
Sheldon: No, I hear you fine. As I was saying, an ordinary magnet has 2 poles. The primary characteristics of a monopoles is that it has only one pole, hence, "monopole".

Wolowitz: I would like a slippery nipple.

Barry Kripke: Hey, Cooper. Read your retraction email. Way to destroy your reputation!

Penny: Leonard, you're back.
Leonard: Yeah, I just stopped by to say… [Penny grabs Leonard and kisses him] Yeah, so, hi!
Penny: Hi! [They stumble into her apartment while kissing]

Leonard: Hey. Listen, since we got, you know, interrupted last night, I didn't have a chance to give you this.
Penny: Oh, Leonard, you shouldn't have. Oh, boy! What is it?
Leonard: It's a snowflake. From the North Pole.
Penny: Are you serious?
Leonard: Uh-huh. It'll last forever. I preserved it in a one percent solution of polyvinyl acetal resin.
Penny: Oh, my God. That's the most romantic thing anyone's ever said to me that I didn't understand.
Leonard: It's actually a pretty simple process. You see, cyanoacrylate are monomers which polymerize on... [Penny kisses him]

Crawley: I've been studying insects since I was 8 years old. You know what they use to call me in school? Creepy Crawley!

Leonard: Nothing flamed out. We don't have to have sex every night, you know.
Howard: You don't have to, but it's highly recommended.
Raj: Yeah, take advantage of that window of opportunity before it slams shut on your little dinky.

Leonard: It's not a matter of opportunity. We're getting to know each other. There's a learning curve.
Howard: What's there to learn? You get naked, do nasty things to each other, then somebody makes scrambled eggs and salami. Easy peasy.

Sheldon: Perhaps what Leonard is obliquely referring to is the occurrence of some sort of sexual dysfunction.
Raj: Okay, who had Leonard gets a floppy disk?
Sheldon: Oh, a clever, albeit obsolete, euphemism for insufficient blood flow to the male sex organ.

Sheldon: As I was saying, you and Leonard had a disappointing sexual encounter. Earlier this evening, Leonard characterized it as just fine. So what you're seeing here is a continuation of the mocking that followed.
Penny: Okay. Yeah, well, I'm just gonna go eat my dinner elsewhere. Maybe an airplane headed for a mountainside.

Penny: What did you tell them?
Leonard: Nothing bad, just that last night was fine.
Penny: Fine? You said it was fine?
Leonard: Yeah, it's a perfectly good word. You put it in front of wine or dining, and you've really got something.

Penny: It was ... okay.
Leonard: Okay?
Penny: Yeah, it's a perfectly good word. I mean, you put it in front of dokay and you really got something.

Raj: What's that?
Howard: Sounds like a cricket.
Sheldon: Hang on. Based on the number of chirps per minute and the ambient temperature in this room, it is a snowy tree cricket.
Howard: Oh, give me a frickin' break. How could you possibly know that?
Sheldon: In 1890, Emile Dolbear determined that there was a fixed relationship between the number of chirps per minute of the snowy tree cricket and the ambient temperature. A precise relationship that is not present with ordinary field crickets.
Raj: How do you know what the exact temperature of the room is?
Sheldon: Under the terms of my roommate agreement with Leonard, I've had unilateral control of the thermostat ever since the sweaty night of '06.

Howard: Okay, you were right about Wolverine and bone claws, but you're wrong about the cricket.
Sheldon: Howard, don't embarrass yourself, the science chirps for itself. Humorous word play.