Sheldon: The entire nation dedicated a decade of effort and treasure to put a man on the moon.
Wolowitz: Well, my fellow Americans, before this year is out we will put a Wolowitz on one of America's top models.
Raj: And a large number of people will believe it never happened

Leonard: Just apologize to him, okay?
Penny: What? I'm not going to apologize to that nut-case.
Leonard: Come on, it's easy. He'll even tell you what to say

Wolowitz: Over the years, we've formulated a number of theories about how he might reproduce. I'm an advocate of mitosis.
Penny: I'm sorry?
Wolowitz: I believe one day Sheldon will eat an enormous amount of Thai food and split into two Sheldons.
Leonard: On the other hand, I think Sheldon might be the larval form of his species and someday he'll spin a cocoon and emerge two months later with moth wings and an exoskeleton

Ramona: You're not going to Halo night
Sheldon: Yes, I am. It's Wednesday. Wednesday's Halo night.
Ramona: Didn't a great man once say, "Science demands nothing less than the fervent and unconditional dedication of our entire lives"?
Sheldon: He did.
Ramona: And who was that great man?
Sheldon: Me. Sorry, Leonard.
Leonard: Seriously? You're not coming?
Sheldon: You heard her. How can I argue with me?

Penny [after witnessing Sheldon and Ramona together]: You probably don't want to go in there.
Leonard: Why? What are they doing?
Penny: The only way I could explain it would be in a therapist's office with dolls

Sheldon: Looking out at your fresh young faces, I remember when I, too, was deciding my academic future as a lowly graduate student. Of course, I was fourteen. And I had already achieved more than most of you could ever hope to, despite my 9:00 bedtime. Now, there may be one or two of you in this room who has what it takes to succeed in theoretical physics, although it's more likely that you'll spend your scientific careers teaching fifth graders how to make papier-mâché volcanoes with baking soda lava.
Leonard: Oh, good God.
Sheldon: In short, anyone who told you that you would someday be able to make some significant contribution to physics, played a cruel trick on you—a cruel trick indeed. Any questions? ... Of course not. I weep for the future of science

Rajesh: Isn't there a University policy against dating graduate students?
Leonard: No. If you can talk to them, you can ask them out.
Rajesh: Damn, there's always a catch

Sheldon: Please, please, I don't have a lot of time. Ramona finally dozed off and I need you to help me get rid of her.
Penny: Get rid of her how?
Sheldon: I don't know, but apparently I'm in some kind of relationship, and you seem to be an expert at ending them.
Penny: Excuse me?
Sheldon: I see man after man leaving this apartment, never to return.

Sheldon: How am I going to get to work?
Leonard: Take the bus.
Sheldon: Oh, I can't take the bus anymore. They don't have seatbelts, and they won't
let you lash yourself to the seat with bungee cords.
Leonard: You tried to lash yourself to the seat with bungee cords?
Sheldon: I didn't try; I succeeded.

Sheldon: Leonard, have you ever wondered why my little toes and lateral incisors are significantly smaller than the average for someone of my size?
Leonard: I wonder a lot of things about you Sheldon, but not that

They gave him an assistant? If I want a new pen I have to go to the bank with wire cutters

Wolowitz [about Raj]

Raj: Did you see my limo downstairs?
Leonard: Yeah.
Raj: It's bigger than the house my grandfather grew up in.
Leonard: Great.
Raj: It has more food, too

TBBT Quotes

Sheldon: I recently read that during World War Two, Joseph Stalin had a research program to create supersoldiers by having women impregnated by gorillas.
Howard: What a sick use of science.
Raj: Hey, as long as the baby's healthy.
Amy: I wonder if Stalin considered any other animals.
Leonard: Hippos are the deadliest creature. A half-human, half-hippo soldier would be pretty badass.
Howard: Yes, but when they're hungry-hungry, you can stop them with marbles.
Sheldon: Yeah, the correct animal for interspecies supersolider is koala. You would wind up with an army so cute it couldn't be attacked.

Raj: Well, to paraphrase Shakespeare: It's better to have loved and lost than to stay home every night and download increasingly shameful pornography.
Penny: Oh... you poor baby.
Raj: What's wrong with me, Penny?
Penny: Nothing, nothing. You know, if we weren't friends - and you hadn't brought up that creepy pornography story - I'd be on you like the speed of light squared on matter to make energy.
Raj: Hey, you totally got that right. E = MC squared.
Penny: I listen. I have no idea what it means, but I listen.