Raj: I don't like bugs, okay. They freak me out.
Sheldon: Interesting. You're afraid of insects and women. Ladybugs must render you catatonic.

Sheldon: Scissors cuts paper, paper covers rock, rock crushes lizard, lizard poisons Spock, Spock smashes scissors, scissors decapitates lizard, lizard eats paper, paper disproves Spock, Spock vaporizes rock, and as it always has, rock crushes scissors.

Stuart: Oh, Sheldon, I'm afraid you couldn't be more wrong.
Sheldon: More wrong? Wrong is an absolute state and not subject to gradation.
Stuart: Of course it is. It's a little wrong to say a tomato is a vegetable, it's very wrong to say it's a suspension bridge.

Howard: You know, I'm really glad you decided to learn Mandarin.
Sheldon: Why?
Howard: Once you're fluent, you'll have a billion more people to annoy instead of me.

Sheldon: Why are you crying?
Penny: Because I'm stupid.
Sheldon: That's no reason to cry. One cries because one is sad. For example, I cry because others are stupid, and that makes me sad.

Howard: Sheldon, don't take this the wrong way, but, you're insane.
Leonard: That may well be, but the fact is it wouldn't kill us to meet some new people.
Sheldon: For the record, it could kill us to meet new people. They could be murderers or the carriers of unusual pathogens. And I'm not insane, my mother had me tested.

Amy: Okay, what is going on?
Penny: We just want you to be prepared for any surprises that could happen tomorrow.
Amy: What surprises?
Bernadette: We don't want to spoil anything, but you should know that Sheldon said he's ready to be physical.
Amy: You shut your damn mouth! You actually heard him say this?
Penny: Yes, he said he wants to do something to show you how much you mean to him.
Amy: I can't believe it. I don't know what to say.
Bernadette: Well, we're really happy for you and we know how much-
Amy: I do know what to say. Let's get me waxed!

Raj: Amy, good luck getting these guys excited about a dinner with a theme. I gave up when no one cared about my Tom Hanks-Giving.

Zack: One question. How can you be sure it won't blow up?
Leonard: The laser?
Zack: The moon.

Raj: Oh man, first monster I see I'm gonna sneak up behind him, whip out my wand and shoot my magic all over his ass!
Stuart: Do you hear yourself when you say these things?

Sheldon: May I say something?
Leonard: Not right now, Sheldon.
Sheldon: But I think it may be comforting.
Leonard: Buddy-
Howard: No, it's okay. What?
Sheldon: When I lost my own father, I didn't have any friends to help me through it. You do.

Sheldon: Thank you, Dr. Fowler. I have a very long and somewhat self-centered speech here. But I'd like to set it aside.
Penny: Yeah!
Howard: Way to go!
Sheldon: Because this honor doesn't just belong to me. I wouldn't be up here if it weren't for some very important people in my life. Beginning with my mother, father, meemaw, brother and sister. And my other family, who I'm so happy to have here with us. Is that Buffy the Vampire Slayer? I was under a misapprehension that my accomplishments were mine alone. Nothing could be further from the truth. I have been encouraged, sustained, inspired and tolerated not only by my wife, but by the greatest group of friends anyone ever had. I'd like to ask them to stand. Dr. Rajesh Koothrappali. Dr. Bernadette Rostenkowski-Wolowitz. Astronaut Howard Wolowitz. And my two dearest friends in the world, Penny Hofstadter and Dr. Leonard Hofstadter. I was there the moment Leonard and Penny met. He said to me that their babies would be smart and beautiful. And now that they're expecting, I have no doubt that that will be the case.
Penny: Thanks, Sheldon. I-I haven't told my parents yet, but thanks.
Sheldon: Oh. I'm sorry. Don't tell anyone that last thing. That's a secret.
Howard, Bernadette, Raj, Penny, Leonard, I apologize if I haven't been the friend you deserve. But I want you to know in my way, I love you all. And I love you. Thank you.

Leonard: Penny, as a scientist, my job is to figure out why things happen. But I don't think I'll ever understand how someone like me could get to be with someone like you. You know maybe I don't need to understand it, I just need to be grateful. I love you, Penny.

Sheldon: Woman, you are playing with forces beyond your ken.
Penny: Yeah, well your Ken can kiss my Barbie.

Leonard: What am I supposed to do?
Penny: Err, keep your mouth off other women.