Alex: Sheldon thinks the approach in this paper might change the way we calculate ferromagnetic hysteresis.
Penny: Oh, it's about time. I hated the old way.

Leonard: Where are we going?
Penny: My limbic system wants to take your pants off.

Sheldon: Settle down there, fake Wolowitz. No one likes a kiss-up.

Sheldon: Penny, please don't hurt my friend.

Sheldon: If you're going to replace Wolowitz, I need to know a little bit more about you.
Stuart: All right.
Sheldon: Wolowitz went to MIT. What's your educational background?
Stuart: I went to art school.
Sheldon: Equally ridiculous. Let's go.

Sheldon: Excuse me. This is not about protecting my friend. Im a big fan of homeostasis. Do you know what that is?
Penny: Of course not.
Sheldon: Homeostasis refers to a systems ability to regulate its internal environment and maintain a constant condition of properties like temperature or pH.
Penny: Worst bedtime story ever!

Sheldon: Leonard, the transformers teach us that things are not always what they appear to be. You know, like, a semi truck might be an alien robot, or someone in a romantic relationship might feel differently than they appear to.

Penny: Ooh, one gravy boat.
Amy: That's from Sheldon. He told me he had it engraved.
Bernadette: In the event of divorce, please return to Sheldon Cooper.
Penny: One inappropriate, yet I wish I thought of that, gravy boat.

Amy: When I get married, I'm going to register at the UCLA Cadaver Lab.
Penny: Eww, why?
Amy: 'cause I've always wanted a whole human skeleton and they are really spendy.

Penny: I'm not unhappy at all. It's just, I don't know, I've been in love before, but it felt different. But maybe this is a new, better, boring kind of love. Do you ever feel that way about Howard?
Bernadette: Oh, that's not really a fair comparison. I'm basically married to a sexy Buzz Lightyear.

Penny: Amy, you?
Amy: Can't help ya, kid. Whenever I'm around Sheldon, I feel like my loins are on fire. In the good way. Not the urinary tract infection way.

Howard: You're out of your mind, Sheldon.
Sheldon: That's a negative. My mother had me tested. Over.

Leonard: Sheldon, you are not in charge.
Sheldon: That's mighty sassy for a man with a roommate performance review around the corner.

Sheldon: How can she not be sure how she feels? You know, when I have a feeling, I know it. Trains? Love them. Swordfish. I love them, too. They're fish with a sword for a nose.

Sheldon: FYI, secret keeping? Hate it. Hand-holding? Not a fan. Hammerhead shark? I love that thing. Yeah, it's another fish with a tool on its head.