Penny singing "Out Tonight"
Leonard: What the hell is that?
Sheldon: I don't know, but if cats could sing ... they'd hate it too.

Leonard: My parents focused on celebrating achievements and being expelled from a birth canal was not considered one of them.

Leonard: If you don't have any other plans, do you want to join us for Thai food and a Superman movie marathon?
Penny: A marathon? Wow, how many Superman movies are there?
Sheldon: You're kidding, right?

Raj: (Strangling Howard) I am Shiva the Destroyer, I will have the woman.
Howard: I'm warning you, I took Judo at math camp.

Penny: What is this?
Leonard: Oh, careful. That's my original series Battlestar Galactica flight suit.
Penny: Oh, why didn't you wear it on Halloween?
Leonard: Because it's not a costume, it's a flight suit.

Christy: Mmm! There's my little engine that could.
*Howard makes train noise*
Sheldon: There's one beloved children's book I'll never read again.

Penny: (crying) How could he do that?
Leonard: Oh, you did throw an 80-gig iPod-- Yeah, no, how could he do that?

Penny: OK, I have a problem!
Sheldon: It's called carpal tunnel syndrome, and quite frankly, you deserve it.

Penny: I'm running really late (to work).
Sheldon: Then I have a simple solution: Go up to the roof, hop over to next building, there's a small gap, don't look if you suffer of vertigo, and use their stairwell.
Penny: You are joking, right?
Sheldon: Oh, I never joke when it comes to vertigo.

Leonard: (Helping Althea with the crossword puzzle) One across is Aegean, eight down is Nabokov, 26 across is MCM, fourteen down is-- move your finger, phylum, which makes 14 across Port-au-Prince. See, Papa Doc's capital idea, that's Port-au-Prince. Haiti.

Leonard: You know, Penny, we make such a good team, maybe we could enter a couple of Halo tournaments sometime.
Penny: Or we could just have a life.

Raj: (Talking about Howard) Oh, if only I had his confidence. I have such difficulty speaking to women, or around women, or at times even effeminate men.

Raj: Are there any chopsticks?
Sheldon: You don't need chopsticks, this is Thai food.
Leonard: Here we go.
Sheldon: Thailand has had the fork since the latter half of the nineteenth century. Interestingly they don't actually put the fork in their mouth, they use it to put the food on a spoon which then goes into their mouth.
Leonard: Ask him for a napkin, I dare you.

Leonard: Excuse me, your entire argument is predicated on the assumption that Superman's flight is a feat of strength.
Sheldon: Are you listening to yourself, it is well established that Superman's flight is a feat of strength, it is an extension of his ability to leap tall buildings, an ability he derives from Earth's yellow Sun.
Howard: Yeah, and you don't have a problem with that? How does he fly at night?
Sheldon: Uh, a combination of the moon's solar reflection and the energy storage capacity of Kryptonian skin cells.

Howard: Oh boy, I was afraid of this.
Leonard: What?
Howard: These instructions are a pictographic representation of the least imaginative way to assemble these components. This right here is why Sweden has no space program.