Sheldon: You're in my bedroom.
Penny: Yeah, Leonard gave me an emergency key.
Sheldon: People can't be in my bedroom.

Sheldon: I'm hell-bent on catching a cyber criminal, not the common cold.

Sheldon: Howard, I'm gonna need another mandarin lesson, I obviously didn't make my point with those people.
Howard: For God's sake, Sheldon, if you don't like the tangerine chicken, don't order the tangerine chicken.
Sheldon: I like tangerine chicken, I'm just not getting tangerine chicken.

Penny: No, I can't. Sheldon, honey, I don't want things to be weird between us.
Sheldon: Won't it also be 'weird' if I have to say hello to you every morning on my way to work and you're living in a refrigerator box and washing your hair with rainwater?

Sheldon: There's a lot of harm in trying something new. That's why we test out drugs and cosmetics on bunny rabbits.

Sheldon: # Nobody knows the trouble I've seen. Nobody knows my sorrow. #

Sheldon: How would one measure a sense of humor? A humormometer?

Penny: I found the decaf.
Stuart: Oh, great.
Sheldon: Herbal tea for me, please.

Penny: How is that not talking to me like I'm an idiot? It's my friend, it's my couch, and it's my freakin' life!
Sheldon: It's also your roll.

Howard: What's this? (hand movement)
Sheldon:That's what you did. I assumed, as in a number of languages, that the gesture was part of the phrase.
Howard: Well, it's not.
Sheldon: Why am I supposed to know that? As the teacher, it's your obligation to separate your personal idiosyncrasies from the subject matter.

Leonard: Okay, I'm going ask you one more time. We did the work together, let's present the paper together.
Sheldon: And I'm telling you for the last time, it's pandering, it's undignified, and bite me.

Penny: Okay. Hang on. Are you saying some day that you and Amy might actually get physical?
Sheldon: It's a possibility.

Raj: (Talking about Leslie Winkle) I think she's smoking hot.
Howard: I'd hit that!
Sheldon: You'd hit particulate soil in a colloidal suspension. (Seeing Howard's confusion) Mud.

Sheldon: *knock knock knock* Wil Wheaton!
*knock knock knock* Wil Wheaton!
Wait, how many was that?

*Knock, Knock*
Leonard: Who is it?
Amy: Amy Farrah Fowler.
Sheldon: Darn, she found me.
Leonard: She's been here before.
Sheldon: The only flaw in an otherwise perfect plan. Now get my back, Jack.
Leonard: What do you want me to do?
Sheldon: Tell her I'm not here.
Leonard: Where are you?
Sheldon: I don't know. You'll have to devise a scenario that plausibly explains my absence keeping in mind that the key to a good lie lies in the details.
*Later, Leonard answers the door to Amy*
Leonard: Hi, Amy. Sheldon's not here.
Amy: All right.
Sheldon (to Leonard): Way to go on the details.