Sheldon: I need your help in a matter of semiotics.
Penny: What?
Sheldon: Semiotics, the study of signs and symbols as a branch of the philosophy related to linguistics.
Penny: Okay, honey, I know you think you are explaining yourself, but you're really not

Penny: This is the best cobbler ever!
Mary: You know what the secret ingredient is?
Penny: Love?
Marry: Lard

Sheldon: This car weighs, let's say, 4,000 pounds. Now add 140 for me, 120 for you...
Penny: 120?!
Sheldon: Oh, I'm sorry. Did I insult you? Is your body mass somehow tied into your self-worth?

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?

Penny: So, what do you guys do around here?
Sheldon: Well, today we tried masturbating for money

Penny: And on top of everything else, I'm all gross from moving. My stupid shower doesn't even work.
Leonard: Our shower works.
Penny: Really? Would it be totally weird if I used it?
Sheldon: Yes.
Leonard: No!
Sheldon: No?
Leonard: No.
Sheldon: No

Penny: I'm a vegetarian. Well, except for fish, and the occasional steak. I love steak!
Sheldon: Well, that's interesting. Leonard can't process corn

Penny: I'm a Sagittarius, which probably tells you way more than you need to know.
Sheldon: Yes, it tells us that you participate in the mass cultural delusion that the sun's apparent position relative to arbitrarily defined constellations at the time of your birth somehow affects your personality.
Penny: Participate in the what?

TBBT Quotes

Penny: What actor holds the record for being named People magazine's Sexiest Man Alive?
Sheldon: William Shatner!
Leonard: I don't think it's Shatner.
Sheldon: Then it's got to be Patrick Stewart

Amy: Sheldon, there's something else I've been wanting to say, but before I do, I just... I want you to know that you don't have to say it back.I know you're not ready, and I don't want you to say it just because social convention dictates...
Sheldon: I love you, too.
Amy: You said it.
Sheldon: There's no denying I have feelings for you that can't be explained in any other way. I briefly considered that I had a brain parasite. But that seems even more far-fetched. The only conclusion was love.