Sheldon: What is the best number? By the way, there's only one correct answer.
Raj: 5,318,008?
Sheldon: Wrong. The best number is 73. [short silence] You're probably wondering why.
Leonard & Howard: No, no, we're good.
Sheldon: 73 is the 21st prime number, its mirror 37 is the 12th and its mirror 21 is the product of multiplying, hang on to your hats, 7 and 3. Did I lie?
Leonard: We get it. 73 is the Chuck Norris of numbers.
Sheldon: Chuck Norris wishes. In binary, 73 is a palindrome, 1001001, which backwards is 1001001, exactly the same. All Chuck Norris gets you backwards is Sirron Kcuhc.
Raj: Just for the record, when you enter 5,318,008 in a calculator, upside down it spells boobies.

Sheldon: That's going to make me a chick magnet and I'm so busy as it is.

Penny: Really? On top of everything, you're afraid of birds?
Sheldon: Its called ornithophobia and someday it will be recognized as a true disability, and the landlord will be required by law to put a giant net over the building. Which is unfortunate because I have a fear of nets.

Raj: Look at that. You've known you're gonna be a father for less than a day and you're already stepping up.
Leonard: I'm telling you, you got this.
Howard: Maybe you're right.
Sheldon: Of course he's right. You and I both know how hard it is growing up without a father. That's why I'm confident you're gonna be the best dad you can be.
Howard: Thank you, Sheldon.
Sheldon: You're welcome. And if he has twins, we can do all kinds of neat experiments on them.

Amy: So, you feeling better?
Penny: Not really.
Amy: Sheldon, you have a guest who's upset.
Sheldon: I'll make tea.
Penny: Sweetie, it's OK. I don't want tea.
Sheldon: It's not optional.

Penny: Hey Sheldon, whattcha got there a new comic book?
Sheldon: Old comic book. I just got it from the safe deposit box.
Penny: What do you have a safe deposit box for?
Sheldon: Old comic books.

Penny: When I was a senior in high school, one of my friends heard I was gonna be named head cheerleader, I was so excited. My mom even made me a celebration pie. Then they named stupid Valerie Mossbacher head cheerleader, big old slutbag.
Sheldon: Are you saying that you think a celebration pie is even remotely comparable to a Nobel Prize?
Penny: Well, they're pretty tasty.
Sheldon: And on a different, but not unrelated topic, based on your current efforts to buoy my spirits, do you ever truly believe that you were fit to be a cheer leader?

Sheldon: Leonard, make Howard stop being naked in my spot!

Sheldon: Oh look, it's Harry Potter and 98% of Sorcerer's stone.

Penny: So, how've you been?
Sheldon: Well, my existence is a continuum, so I've been what I am at each point in the implied time period.

Sheldon: Question: Where are my Pants?

Sheldon: Well that's no threat, my mother's always wanted a grandchild.
Penny: Really? Your deeply religious born-again Christian mother wants a test-tube grandbaby born out of wedlock?
Sheldon: Curses.

Sheldon: Sorry, I'm late.
Leonard: What happened?
Sheldon: Nothing. I just didn't want to come.

Sheldon: Amy Farrah Fowler has asked me to meet her mother.
Leonard: Yeah, so?
Sheldon: What does that mean?
Leonard: Well, you know how you're always saying Amy is a girl who is your friend but not your girlfriend?
Sheldon: Uh huh.
Leonard: Well, you can't say that any more.

Raj: (Talking to the snake) Let's go to the biology lab and find you some nice yummy mice.
Sheldon: I tried to scare an Indian with a snake. Come on, Cooper. You're better than this.