Leonard: So now let's bring out theoretical physicist, Dr, Sheldon Cooper.
Sheldon: Hello, female children. Allow me to inspire you with a story about a great female scientist. Polish-born, French-educated Madame Curie. Co-discover of radioactivity. She was a hero of science until her hair fell out, her vomit and stool became filled with blood, and she was poisoned to death by her own discovery. With a little hard work, I see no reason why that can't also happen to any of you. Are we done? Can we go?

Howard: I'm just afraid if I respond, then they'll know I got it.
Raj: Oh, dude. The minute you opened that e-mail, they knew you got it. I mean, they're probably looking at you through the camera right now. (Howard closes the laptop, Raj re-opens it and looks at the camera) I love America!

Bernadette: Sheldon, when was the last time you got any sleep?
Sheldon: I don't know. 2 or 3 days. Not important. I don't need sleep, I need answers. I need to determine where in this swamp of unbalanced formulas squatteth the toad of truth.
Penny: Toad of truth? Is that a physics thing?
Leonard: No, that's a crazy thing.

Penny: Sheldon, what is wrong with you?
Sheldon: Not much. Although, I can be faulted for being overly fond of koala bears. I don't know what it is, but when they start munching on eucalyptus, I just melt inside.

Leonard: Did you get to the chapter where she staged the Easter Egg Hunt with no eggs to see how long I'd keep looking? The answer, by the way, June.

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.

Penny: Seriously, none of you liked it?
Bernadette: I thought it was brave. Does that count as liking it?
Penny: You know, how come nobody's talking about Howard's dopey haircut?
Bernadette: I think he looks cute.
Howard: And I think you're cute.
Raj: I think you're both cute.
Penny: I think I hate all of you nerds.

Amy: I-I thought Wil was marrying us.
Sheldon: Wolowitz got us an upgrade.
Amy: Another sci-fi guy with a beard. Seems lateral, but okay.

Raj: I never thought I would see Sheldon enjoying himself around babies so much.
Amy: Yeah, how about that?
Raj: So he just happened to stumble upon a book about experimenting with them the same day we were hanging out with Howard's kids?
Amy: Yep, don't overthink it.

Raj: Okay, I have a request to make.
Amy: And now he can talk. I want to cut open your brain and see what the heck is going on in there.

Sheldon: Gentlemen, I think I've come up with a fun way to get young people interested in science. Physics Mad-Libs. Now, give me a number.
Leonard: Five.
Sheldon: Uh-huh. And an irrational constant.
Howard: E.
Sheldon: And a funny Greek letter.
Raj: Gamma.
Sheldon: I said funny.
Raj: Upsilon?
Sheldon: Good one. And an electrical charge.
Leonard: Positive.
Sheldon: Ha. Perfect. Okay. Get this. Professor Jones told the symposium he had a new method for calculating the mass of a muon. Five times the limit of E to the upsilon as in a ... (laughs uncontrollably) ... Okay. No, no. I'll start over. Professor ... (laughs again).

Amy: Missed one. Now your wish can't come true.
Sheldon: Lucky for you because I wished you were dead.

Sheldon: (Mandarin) Long live concrete? Thank you.

Sheldon: Who's ready to laugh? [Leonard groans] Okay. So Feynman, Einstein and Schrodinger walk into a bar. Feynman says, "It appears we're inside a joke." Einstein replies, "But only to an observer who saw us walk in simultaneously." To which Schrodinger says, "If someone's looking in the window, I'm leaving."
Leonard: [chuckles] That's actually funny.
Raj: You should send that to Jimmy Fallon.

Sheldon: Under normal circumstances I'd say I told you so. But, as I have told you so with such vehemence and frequency already, the phrase has lost all meaning. Therefore, I will be replacing it with the phrase, "I have informed you thusly".