Sheldon: Hello.
Penny: Hello.
Sheldon: Ok, enough with the friendly banter. I believe you know why I am here.
Penny: Oh, I always figured it was to study us, discover our weaknesses, and report back to your alien overlords.
Sheldon: Yes, amusing. Extraordinary intelligence might well appear extraterrestrial to you, but let me be more specific. I believe you know why I am here in the laundry room.

Sheldon: But evolution is not opinion, it's a fact.
Mary Cooper: And that is your opinion.
Sheldon: [to Leonard, Howard and Raj] I forgive you, let's go home.

Sheldon: Hello, Penny. I realize you are currently in the mercy of your primitive biological urges. But, as you have an entire lifetime of poor decisions ahead of you, may I interrupt this one?

Sheldon: Now, Introduction to Physics. What is physics? Physics comes from the ancient Greek word physika. It's at this point that you'll want to start taking notes. Physika means the science of natural things. And it is there, in ancient Greece, that our story begins.
Penny: Ancient Greece?
Sheldon: Hush. If you have questions, raise your hand. It's a warm summer evening, circa 600 BC. You've finished your shopping at the local market, or agora, and you look up at the night sky. There you notice some of the stars seem to move, so you name them planetes, or "wanderer". Yes, Penny?
Penny: Um, does this have anything to do with Leonard's work?
Sheldon: This is the beginning of a twenty six hundred year journey we're going to take together from the ancient Greeks through Isaac Newton to Niels Bohr to Erwin Schrodinger to the Dutch researchers that Leonard is currently ripping off.
Penny: Twenty six hundred years?
Sheldon: Yeah, give or take. As I was saying, it's a warm summer evening in ancient Greece…

Penny: I have to go to the bathroom.
Sheldon: Can't you hold it?
Penny: Not for twenty six hundred years.

Sheldon: Now remember, you were given powerful pain medication and a muscle relaxer, so don't operate heavy machinery, and try not to choke on your own drool. [goes to leave]
Penny: Wait! You have to help me get into bed. [laughs] "Sheldon has to help me get into bed". Bet you thought I'd never say that!
Sheldon: Yes. Charmed. Your drug-addled candor knows no bounds. [helps Penny into bed]
Penny: You know people think you are this weird robot man who's so annoying all the time and you totally are. But then it's like that movie Wall-E at the end. You're so full of love and you can save a plant and get fat people out of their floaty chairs.
Sheldon: That's a fairly labored metaphor but I appreciate the sentiment behind it.

Sheldon: What are they doing here?
Leonard: We came to apologize again and bring you home. So why don't you pack up your stuff, and we'll head back?
Sheldon: No, this is my home now. Thanks to you, my career is over, and I will spend the rest of my life here in Texas trying to teach evolution to creationists.
Mary Cooper: You watch your mouth, Shelly. Everyone's entitled to their opinion.
Sheldon: But evolution is not opinion, it's a fact.
Mary Cooper: And that is your opinion.

Sheldon: And look over here, "shrimp in mobster sauce". What is mobster sauce?
Leonard: It's obviously a typo.
Sheldon: Perhaps. Perhaps this restaurant's now a front for organized crime. For all we know, the mobster sauce contains actual chunks of deceased mobsters.
Raj: No, no, no, no. I think it just means it's the kind of sauce that mobsters like.
Howard: It doesn't mean any of that. It's a typo!

Sheldon: That's not afternoon. That's prevening.
Howard: What?
Sheldon: It's a time of day I invented. It better defines the ambiguous period between afternoon and evening. Prevening. I'm fairly certain it will catch on as it fills a desperate need.
Raj: Right, okay. What are you doing tomorrow prevening?
Sheldon: Well, tomorrow's Saturday. Saturday night is laundry night, so I'll be spending the prevening pre-sorting and pre-soaking.

Sheldon: Professor, can you identify our cricket?
Crawley: Of course I can. I can identify every insect and arachnid on the planet. Not that that's gonna keep me from having to move in with my daughter in Oxnard. And we're not talking Oxnard at the beach. No, we're talking Oxnard in the onion fields!

Bernadette: Sheldon, when was the last time you got any sleep?
Sheldon: I don't know. 2 or 3 days. Not important. I don't need sleep, I need answers. I need to determine where in this swamp of unbalanced formulas squatteth the toad of truth.
Penny: Toad of truth? Is that a physics thing?
Leonard: No, that's a crazy thing.

Penny: So, how you been?
Sheldon: Well, my existence is a continuum, so I've been what I am at each point in the implied time period.
Penny: You're just coitusing with me, aren't you?
Sheldon: Bazinga!

Sheldon: I should've brought an umbrella.
Leonard: What for? It's not going to rain.
Sheldon: I know that, but with skin as fair as mine, moon burn is a real possibility.
Howard: That's a bazinga, right?
Sheldon: One of my best, don't you think?

Penny: Sing Soft Kitty to me.
Sheldon: Soft Kitty is for when you’re sick. You're not sick.
Penny: Injured and drugged is a kind of sick.
Sheldon: [sings] Soft kitty, warm kitty, little ball of fur…
Penny: Wait, wait. Let's sing it as a round. I'll start. [sings] Soft kitty, warm kitty, little ball of fur… See that's where you come in. I'll start over. [sings] Soft kitty, warm kitty, little ball of fur… I've got all night, Sheldon. Soft kitty, warm kitty…
Both: [sing] ...little ball of fur, happy kitty, sleepy kitty, purr, purr, purr.

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]