Sheldon: I'm confused. If there's no costume parade, what are we doing here?
Leonard: We're socializing. Meeting new people...
Penny: Well, I ran into him last week and, he was just, all apologetic, about how he's changed, and he was just going on and on and, and I believed him, and I'm an idiot because I always believe guys like that and... I can't go back to my party because he's there, and I know you don't want to hear this but I'm upset and I'm really drunk and I just want to talk...
[Bursts into tears and rests head on Leonard's shoulder]
Leonard: There, there.
Penny: God, what is wrong with me?
Leonard: Nothing; you're perfect.
Penny: I'm not perfect.
Leonard: Yes, you are.
Penny: You really think so, don't you?
[She kisses him]
Leonard: How much have you had to drink tonight?
Penny: Just... a lot.
Leonard: Are you sure that your being drunk, and your being angry with Kurt doesn't have something to do with what's going on here?
Penny: It might. Boy, you're really smart.
Leonard: Yeah, I'm a frickin' genius.
Penny: Leonard, you are so great. Why can't all guys be like you?
Leonard: Because if all guys were like me, the human race couldn't survive.
Leonard: Why don't you just tell people you're a zebra?
Sheldon: Why don't you just tell people you're one of the seven dwarves?
Leonard: Because I'm Frodo!
Sheldon: Yes... Well... I'm the Doppler effect!
Sheldon: Like Jane Goodall observing the apes, I initially saw their interactions as confusing and unstructured, but patterns emerge, they have their own... language if you will.
Leonard: Go on.
Sheldon: Well, it seems that the newcomer approaches the existing group With the greeting: "How wasted am I?" which is met with an approving chorus of: "Dude!"
Leonard: Then what happens?
Sheldon: That's as far as I've gotten.
Cheryl: [in bed with Raj]
Cheryl: I have to say... you are an amazing man. You're gentle... and passionate... and, my God! you are such a good listener.
Raj Koothrappali: [dressed as Thor, Norse God of Thunder] Hey. Sorry I'm late but my hammer got stuck in the door on the bus.
Leonard: You went with Thor?
Raj Koothrappali: What? Just because I'm Indian I can't be a Norse God? No, no, no Raj has to be an Indian God. That's racism. I mean, look at Wolowitz. He's not English but he's dressed like Peter Pan. Sheldon is neither sound nor light but he's obviously the Doppler effect.
Howard Wolowitz: I'm not Peter Pan. I'm Robin Hood.
Raj Koothrappali: Really? Because I saw Peter Pan and you're dressed exactly like Cathy Rigby. She was a little bigger than you but it's basically the same look, man.
Raj Koothrappali: OK, if no-one else will say it, I will. We really suck at paint-ball.
Howard Wolowitz: That was absolutely humiliating.
Leonard: Oh, come on, some battles you win, some battles you lose.
Howard Wolowitz: Yes, but you don't have to lose to Kyle Bernstein's Bar-Mitzvah party.
Leonard: I think we have to acknowledge those were some fairly savage preadolescent Jews.
Sheldon: No, we were annihilated by our own incompetent and the inability of some people to follow the chain of command.
Leonard: Sheldon, let it go!
Sheldon: No, I want to talk about the fact that Wolowitz shot me in the back.
Howard Wolowitz: I shot you for good reason. You were leading us into disaster.
Sheldon: I was giving clear, concise orders.
Leonard: You hid behind a tree yelling: "Get the kid in the yarmulke; get the kid in the yarmulke!"
Raj Koothrappali: If only I had his confidence. I have such difficulty speaking to women. Or around women. Or at times even effeminate men.
Leonard: Are misfiring neurons in your hippocampus preventing the conversion from short term to long-term memory?
Leonard Hofstadter: I'm going to assert my dominance face-to-face.
Sheldon Cooper: Face-to-face? Are you gonna wait for him to sit down, or are you gonna stand on the coffee table?
Sheldon Cooper: Maybe she wants to be friends and he wants something more.
Leonard Hofstadter: Then he and I are on equal ground.
Sheldon Cooper: Yes, but you're much closer to it than he is.
Sheldon Cooper: Aren't you afraid I'll embarrass you?
Leonard Hofstadter: Yes, but I need a wingman.
Sheldon Cooper: Alright, but if we're going to use flight metaphors, I'm much more suited to being the guy from the FAA analyzing wreckage.
Leonard Hofstadter: Of course we're all animals, but some of us have climbed a little higher on the evolutionary tree.
Sheldon Cooper: If he understands that, you're in trouble.
Kurt: So, what? I'm unevolved?
Sheldon Cooper: You're in trouble.
Howard Wolowitz: Hey guys, check out the sexy nurse. I believe it's time for me to turn my head and cough.