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

Penny: I'm a Sagittarius, which probably tells you way more than you need to know...
Sheldon:Yes... it tells us that you participate in the mass cultural delusion that the sun's apparent position relative to arbitrarily defined constellations at the time of your birth somehow affects your personality.
Penny: Participate in the what?
Leonard: What he means is that wouldn't be his first guess.
Penny: Yeah, a lot of people think I'm a water sign.

Penny: Leonard, I didn't know you played the cello.
Leonard: Yeah, my parents felt that naming me Leonard and putting me in advanced placement classes wasn't getting me beaten up enough.

Penny: So, you know, isn't there maybe some way you and Sheldon could compromise on this whole presentation thing?
Leonard: No. Scientists do not compromise. Our minds are trained to synthesize facts and come to inarguable conclusions. Not to mention Sheldon is bat-crap crazy.

Sheldon: 15 years old--Dennis Kim is 15 years old, and he's already correcting my work. Today I went from being Wolfgang Amadeus Mozart to--you know--that other guy.
Howard: Antonio Salieri.
Sheldon: Oh, God, now even you're smarter than me.

Sheldon: [about donating sperm] What if she winds up with a toddler who doesn't know if he should use an integral or a differential to solve the area under a curve?
Leonard: I'm sure she'll still love him.
Sheldon: I wouldn't.

Sheldon: Anyway, the housekeeper in the faculty residence didn't speak any English. When I finally managed to convince her I was sick, she said, "Möchtest du eine Darmspülung?"
Penny: What does that mean?
Sheldon: Based on what happened next, I assume it means, "Would you like an enema?"

Sheldon: At this point I should inform you that I intend to form my own team, and destroy the molecular bonds that bind your very matter together, and reduce the resulting particulate chaos to tears.
Leonard: Thanks for the heads up.
Sheldon: You're welcome. [starts to leave] One more thing.
Leonard: Yes?
Sheldon: It's on, bitch.

Sheldon: Checkmate.
Leonard: Argh, again?
Sheldon: Obviously you're not well-suited for three-dimensional chess. Perhaps three-dimensional Candyland would be more your speed.

Sheldon: Engineering--where the semi-skilled laborers execute the vision of those who think and dream. Hello Oompa-Loompas of science.

Sheldon: I was analyzing our lie, and I believe we're in danger of Penny seeing through the ruse.
Leonard: How?
Sheldon: Simple: If she were to log onto www dot socialphysicsgroup dot org forward slash activities forward slash other, click on "Upcoming Events", scroll down to "Seminars", download the PDF schedule, and look for the seminar on molecular positronium, well then, bibbidi-bobbidi-boo, our pants are metaphorically on fire.

Sheldon: I'll have a Diet Coke.
Penny: OK, will you please order a cocktail? I need to practice mixing drinks.
Sheldon: Fine, I'll have a virgin Cuba Libre.
Penny: That's, um, Rum and Coke without the rum.
Sheldon: Yes.
Penny: So, Coke.
Sheldon: Yes. And would you make it Diet?
Penny: [sighs] There's a can in the fridge.
Sheldon: A Cuba Libre generally comes in a tall glass with a lime wedge.
Penny: Then swim to Cuba.
Sheldon: Bartenders are supposed to have people skills.

Sheldon: I'm uncomfortable having been included in your lie to Penny.
Leonard: What was I supposed to say?
Sheldon: You could have told her the truth.
Leonard: That would have hurt her feelings.
Sheldon: Is that a relevant factor?
Leonard: Yes.
Sheldon: Then I suppose you could have agreed to go.
Leonard: And what would I have said afterwards?
Sheldon: I would suggest something to the effect of, "Singing is neither an appropriate vocation nor avocation for you, and if you disagree, I'd recommend you have a CAT scan to look for a tumor pressing on the cognitive processing centers of your brain.
Leonard: I couldn't say that. I would have to say, "You were terrific and I can't wait to hear you sing again."
Sheldon: Why?
Leonard: That's the social protocol. It's what you do when you have a friend who's proud of something they really suck at.
Sheldon: I was not aware of that.
Leonard: Now you are.
Sheldon: Oh. All right. Leonard?
Leonard: Yes?
Sheldon: When we played chess earlier, you were terrific, and I can't wait to play you again.

Sheldon: I've spent the past three-and-a-half years staring at greaseboards full of equations; before that, I spent four years working on my thesis; before that, I was in college, and before that, I was in the fifth grade.

[Discussing a large box of furniture which they have to take to the fourth floor, with the elevator out of order]
Leonard: Well, we'll just have to take it up ourselves.
Sheldon: I hardly think so.
Leonard: Why not?
Sheldon: Well, we don't have a dolly, or lifting belts, or any measurable upper body strength.
Leonard: We don't need strength, we're physicists. We are the intellectual descendants of Archimedes. Give me a lever and a fulcrum and I could lift the earth.
[The package starts falling on him]
Leonard: I don't have this! I don't have this! I DON'T HAVE THIS!
[Sheldon lifts the package off him]
Sheldon: Archimedes would be so proud.
Leonard: Well, do you have any ideas?
Sheldon: Yeah, but they all involve a Green Lantern and a power ring.