Wolowitz: So, what are we watching? Sex in the City, yikes!
Penny: Hey, I happen to love this movie.
Wolowitz: Fine, let's watch it. Maybe all our periods will synchronize

Sheldon: Yes, since their relationship became carnal, Penny has updated his designated term of endearment, distinguishing him from those she calls "sweetie," usually as an attempt to soften a thinly-veiled insult.
Penny: You're boring people, sweetie.
Sheldon: Although sometimes, she omits the veil entirely.

Penny: I give up, he's impossible
Sheldon: I can't be impossible, I exist. I believe what you meant to say is, "I give up, he's improbable."

Penny: I'll tell you what, next french toast day, I'll make you oatmeal
Sheldon: Good lord, are you still gonna be here next french toast day?

Oh man, did the KISS Army repeal "Don't Ask, Don't Tell?"

Penny [after seeing Wolowitz in his goth outfit]

Leonard: Why would you buy peppermint schnapps?
Penny: Because I like peppermint, and it's fun to say schnapps!

Penny: You know, I do understand what you're going through.
Sheldon: Really? Did you just have the Nobel Prize in Waitressing stolen from you?

Leonard [about snuggie gift]: what does this mean?
Penny: Wine, credit cards and late night television are a bad combination

Penny [to comic book store owner]: What would you recommend as a gift for a 13 year old boy?
Stuart: A thirteen year old girl

Penny [at comic book store]: Everyone's staring at me!
Leonard: Don't worry, they're more scared of you than you are of them
Penny: Unlikely

Wolowitz: According to Alicia's Facebook page, she's hooking up with one of the producers on CSI.
Penny: Dead whore on TV, live one in real life.

Penny: It looks like the MySpace page of a 13 year old girl
Leonard: No it doesn't
Wolowitz: Oh please, Dateline could use it to attract predators

TBBT Quotes

Penny: Hey, Sheldon, did you change your Wi-Fi password again?
Sheldon: Yes, it's "Penny, get your own Wi-Fi." No spaces.

Sheldon: Why do you have the Chinese character for "soup" tattooed on your right buttock?
Penny: It's not "soup," it's "courage."
Sheldon: No it isn't. But I suppose it does take courage to demonstrate that kind of commitment to soup.
Penny: How'd you see it? You said you wouldn't look.
Sheldon: Sorry. As I told you, the hero always peeks.