Sheldon: Hello.
Penny: Hello.
Sheldon: Ok, enough with the friendly banter. I believe you know why I am here.
Penny: Oh, I always figured it was to study us, discover our weaknesses, and report back to your alien overlords.
Sheldon: Yes amusing. Extraordinary intelligence might well appear extraterrestrial to you, but let me be more specific. I believe you know why I am here in the laundry room.

Sheldon: She's remarkable.
Leonard: She really is.
Sheldon: How is it that she can remember all those lines, yet as a waitress she can't remember no tomato on my hamburger?

Sheldon: I am a grown man. I am a professional scientist. And I currently occupy the moral high ground.
Mary: Go to your room.
Sheldon: But I occupy the moral high ground.
Mary: Go to your room.
Sheldon: But I'm a professional scientist.
Mary: Go to your room!
Sheldon: *Backs away to his room* I'm a grown man.

Sheldon: Who's Nowitzki?
Ramona: I'm Nowitzki.
Sheldon: Oh, so you want me to share credit with you?
Ramona: Uh huh.
Sheldon: Get out!

Sheldon: But evolution is not opinion, it's a fact. Mary Cooper: And that is your opinion. Sheldon: [to Leonard, Howard and Raj] I forgive you, let's go home.

Sheldon: Careful, Amy. The friend of the enemy's girlfriend is my enemy.
Amy: Really?
Sheldon: You're either with me or against me.
Amy: You wanna take the bus to work?
Sheldon: Maybe there's a third option.

Sheldon: She watched it. I'm gonna get that girl back.
Amy: I only watched it because you emailed it to me with the subject line "This is gonna make you mad."
Sheldon: She was listening through the door. She wants me.

Sheldon: I've learned that 1 in 700,000 people die from general anesthesia.
Leonard: But do you realize that means 699,999 people don't die?
Sheldon: I suppose that's true. You're such a glass half full kind of guy. I'm going to miss that.

Sheldon: Proxima Centauri's the nearest star. The celestial bodies that follow are:
Alpha Centauri A, Toli, Barnard's Star, Wolf 359, Laland 21185, Sirius A, Sirius B, BL Ceti, UV Ceti, Ross 154, Ross 248, Epsilon Eridani, Lac 9352, Ross 128, EZ Aquarii A, EZ Aquarii B, EZ Aquarii C, Procyon A.
Those are the stars that are nearest to me,
Tra la la and fiddle dee dee.

Sheldon: I read an article about Japanese scientists who inserted DNA from luminous jelly fish into other animals; and I thought "Hey! Fish night-lights".
Leonard: Fish night-lights.
Sheldon: It's a billion dollar idea, ssh!

Sheldon: Get back here, you stupid bird, so I can love you.

Sheldon: What are you doing here?
Leonard: I live here.
Sheldon: I have paperwork that says differently.

Sheldon: I must say, Amy, pretending to have intercourse with you has given me a great deal of satisfaction.

Sheldon: I need to sleep here tonight.
Raj: Why?
Sheldon: Howard is a total ass, Bernadette is in Penny's bed, Amy bites and Penny may or may not have coitus with Leonard.
Raj: Okay, come in.

Sheldon: I do feel obligated to point out to you that she did not reject you, you did not ask her out.
Leonard: You're right. I didn't ask her out. I should ask her out.
Sheldon: No! No that was not my point. My point was don't buy a cat.
Leonard: No, but you're right, I should march over there and ask her out.
Sheldon: Oh, goody! We're getting a cat.