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: 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.

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

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

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!

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.

Howard: The other astronauts are being mean to me.
Bernadette: What are they doing?
Howard: Well, like for instance, the other day when I was asleep, one of the guys went on a space walk and glued a big-eyed rubber alien mask to the outside of my window. When I woke up, I screamed for like nine minutes.
Bernadette: Oh, Howie.
Howard: You can see it if you want. It's on YouTube. Google astronaut screams for nine minutes.

Sheldon: My point is, I don't like when things change. So, regardless of your feelings, I would like you to continue dating Leonard. And also, while we're on the subject, you recently changed your shampoo. I'm not comfortable with the new scent. Please stop this madness and go back to green apple.

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.

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: 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.