Sheldon: Why are you crying?
Penny: Because I'm stupid!
Sheldon: Well that's no reason to cry; one cries because one is sad. For example, I cry because others are stupid and it makes me sad.
Sheldon: Where's your notebook?
Penny: I don't have one.
Sheldon: How are you gonna take notes without a notebook?
Penny: I have to take notes?
Sheldon: How else are you gonna study for the tests?
Penny: There's gonna be a test?
Sheldon: Tests. Here, it's college ruled, I hope that's not too intimidating.
Wolowitz: In romance, like show business, always leave them wanting more.
Leonard: What does that mean?
Penny: He struck out.
Wolowitz [about Bernadette]: She wants a commitment, but I'm not sure if she's my type.
Penny: She agreed to go out with you for free. What more do you need?
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.
Sheldon [filling out medical form]: When was your last menstrual period?
Penny: Oh! Next question!
Sheldon: I'll put in progress
Leonard: You know deep down on the inside, Howard's a good guy
Penny: The problem isn't what's on the inside, it's the creepy candy coating
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]