Penny: (Whispers) Here she comes.
Howard: Smart. Whisper so the deaf chick doesn't hear you!

Howard: Sheldon, you're a condescending jerk. Why on earth would I want to do something nice for you?
Sheldon: To go to Jewish heaven.
Howard: Jews don't have heaven.
Sheldon: To avoid Jewish hell?
Howard: Have you met my mother? I live in Jewish hell.

Amy: Jewelry? Seriously? Sheldon, you are the most shallow, self-centered person I have ever met! Do you really think another transparently manipulative - Oh, it's a tiara! Put it on me, put it on me, put it on me, put it on me.

Mary Cooper: It's all themed. There's Jonah and the Whale Watching. All-you-can-eat Last Supper Buffet. And my personal favorite, Gunning with God.

(Howard has just told Mary about his upcoming trip to the International Space Station.)
Mary Cooper: I bet your mom is really proud of you.
Howard: Nope. She says if I don't back out, she's gonna go on a hunger strike. It'd take years before she'd be in any kind of danger, but still.

Bernadette: I'm too small for Twister. And roller coasters. And sitting with my feet on the floor. Hope you enjoyed the prenatal cigarettes, Mom.

Howard: I'm not signing a prenup.
Penny: All right, Howard Wolowitz, listen up! You sign anything she puts in front of you, because you are the luckiest man alive. If you let her go, there is no way you can find anyone else. Speaking on behalf of all women, it is not going to happen, we had a meeting.

(Sheldon knocks on Penny's door three times)
Penny: Who do we love?
Sheldon: Penny. (Knocks 3 times)
Penny: Who do we love?
Sheldon: Penny. (Knocks 3 times)
Penny: Who do we love?
Sheldon: Penny.

Penny: You look beautiful.
Amy: Of course I do, I'm a princess and this is my tiara!

Bernadette: Doesn't he know you have a boyfriend?
Penny: She doesn't have a boyfriend, she has a Sheldon.

Howard: I thought you didn't like Facebook any more.
Sheldon: Don't be silly, I'm a fan of anything that tries to replace actual human contact.

Leonard: Once you open the box it loses its value.
Penny: Yeah, yeah. My mom gave me the same lecture about my virginity. I gotta tell you, it was a lot more fun taking it out and playing with it.

Amy: You are aware that your ritualistic knocking behavior is symptomatic of obsessive-compulsive disorder?
Sheldon: Is not. Is not. Is not.
Amy: Denial. Denial. Denial.

Bernadette: Boy, I don't know if I could be friends with Howie if we broke up.
Howard: Why not?
Bernadette: I'm a very vengeful person.
Howard: Really?
Bernadette: With access to weaponized smallpox.

Leonard: More Halloween candy. Didn't you just buy a bunch of it yesterday?
Penny: Oh, yeah. That's gone. It's a rough month when Halloween and PMS hit at the same time.