Sheldon: I feel renewed. I'm ready to deal with any changes that come my way. [sees Penny] Your hair is different. You changed your hair. I can't take this. I'm out.

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.

Mary Cooper: Thank you, God, for the food we are about to receive and for the nourishment of our bodies and bless the hands that prepared it. Amen.
Sheldon: Given that your hands prepared it, isn't that a little self-serving?
Mary Cooper: You start changing the words to the prayers, next thing you know, you're in a church with a guitar.

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.

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.

Howard: The man impersonating a bear would like you to know that, "Only you can prevent forest fires."
Raj: I don't get it.
Howard: You didn't have Smokey the Bear in India?
Raj: No. Was he anything like Munmun the Mongoose? He taught us not to play with cobras.
Howard: You had to be taught not to play with cobras?
Raj: You had to be taught not to burn down the forest?

Sheldon: Professor, can you identify our cricket?
Crawley: Of course I can. I can identify every insect and arachnid on the planet. Not that that's gonna keep me from having to move in with my daughter in Oxnard. And we're not talking Oxnard at the beach. No, we're talking Oxnard in the onion fields!

Sheldon: It's a shame our society mocks the differently uvulated.

Leonard: No, her bed kind of ... broke.
Sheldon: That doesn't seem likely. Her bed's of sturdy construction. Even the addition
of a second normal size human being wouldn't cause a structural failure, much less a homunculus such as yourself.
Penny: A homunculus?
Leonard: Perfectly formed miniature human being.

Leonard: What would you be if you were attached to another object by an inclined plane, wrapped helically around an axis?
Sheldon: Screwed?
Leonard: There you go.

Raj: If you really want to challenge yourself, you could learn to speak Hindi.
Sheldon: Jab mein aat saal ka tha Maine seekha tha.
Raj: Could you say that in English? I actually, I never learned Hindi.

Penny: Like, what'd you do last night?
Beverly Hofstadter: I had Cuban food at the home of a man with whom I shared unsatisfying intercourse.
Penny: Wow. Okay.
Beverly Hofstadter: And to anticipate your next questions, roasted pork and sideways missionary.
Penny: Sure. Sure. 'Cause you were full.

Amy: Do you need anything else?
Sheldon: You know exactly what I need.
Amy: Fine. [sings and plays autoharp] Soft kitty, warm kitty, little ball of fur. Happy kitty, sleepy kitty, purr, purr, purr.
Sheldon: That's nice. Now in German.
Amy: [sings and plays autoharp] Weiches Kätzchen, warmes Kätzchen, das nie und nimmer murrt. Liebes Kätzchen, müdes Kätzchen, schnurrt, schnurrt, schnurrt.
Sheldon: Great. Now Mandarin.
Amy: [sings and plays autoharp] Ruǎnmiánmián de xiǎo māomī máoróngrōng, kuàilè kēshuì qīngqiǎo māomī, gūlǔ gūlǔ gūlǔ.
Sheldon: Now Navajo.

Penny: How's your life?
Amy: Like everybody else's, subject to entropy, decay and eventual death. Thank you for asking.

Sheldon: You know, the German philosopher Friedrich Nietzsche believed that morality is just a fiction used by the herd of inferior human beings to hold back the few superior men.
Leonard: Thanks, that actually does help.
Sheldon: It's worth noting that he died of syphilis.