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: 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 jut means it's the kind of sauce that mobsters like.
Howard: It doesn't mean any of that. It's a typo!

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]

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: So, how'd you two guys meet?
Zack: My company designs the menus for the Cheesecake Factory.
Leonard: Your company?
Zack: Well, it's my dad's, but me and my sister are VPs.
Leonard: So, menus?
Zack: I know it sounds easy but there's a lot of science that goes in designing them.

Amy: You should also know that all physical contact, up to and including coitus, is off the table.
Sheldon: May I buy you a beverage?
Amy: Tepid water please.
Wolowitz: My God, what have we done?

Zack: Hey, I want to see this laser thing.
Penny: Oh, but what about the party?
Zack: It's a surprise party, doesn't matter when we get there.

Leonard: Don't worry about the moon. We, we set our laser to stun.
Zack: Smart.
Leonard: Now, we'll be able to see the beam when it leaves, but it won't be strong enough when it comes back to be seen by the naked eye.
Zack: (chuckling) Naked.

Penny: When I was a senior in high school, one of my friends heard I was gonna be named head cheerleader, I was so excited. My mom even made me a celebration pie. Then they named stupid Valerie Mossbacher head cheerleader, big old slutbag.
Sheldon: Are you saying that you think a celebration pie is even remotely comparable to a Nobel Prize?
Penny: Well, they're pretty tasty.
Sheldon: And on a different, but not unrelated topic, based on your current efforts to buoy my spirits, do you ever truly believe that you were fit to be a cheer leader?

Leonard: Two degrees, Sheldon. I just want to turn the thermostat two degrees.