Penny: What the hell's going on?
Sheldon: You hypocrite.
Penny: What?
Sheldon: Little Miss Grown-Ups-Don't-Play-With-Toys! If I went into that apartment right now, would I not find Beanie Babies? Are you not an accumulator of Care Bears and My Little Ponies? And who is that Japanese feline I see frolicking on your shorts? Hello, Hello Kitty!

Sheldon: Um, Penny, that's where I sit.
Penny: So, sit next to me.
Sheldon: No, I sit there.
Penny: What's the difference?
Sheldon: "What's the difference"?
Leonard: Here we go.
Sheldon: In the winter that seat is close enough to the radiator to remain warm, and yet not so close as to cause perspiration. In the summer it's directly in the path of a cross breeze created by open windows, there and there. It faces the television at an angle that is neither direct, thus discouraging conversation, nor so far wide to create a parallax distortion. I could go on, but I think I've made my point.

Mrs. Wolowitz: Howard it's the phone!
Howard: I know it's the phone ma! I hear the phone!
Mrs. Wolowitz: Who is calling at this ungodly hour?
Howard: I don't know!
Mrs. Wolowitz: Well ask them why are they calling at this ungodly hour!
Howard: How can I ask them when I'm talking to you?

Penny: Yes, I know men can't fly.
Sheldon: No, no let's assume that they can. Lois Lane is falling, accelerating at an initial rate of 32ft per second, per second. Superman swoops down to save her by reaching out two arms of steel. Ms. Lane, who is now traveling at approximately 120 miles per hour, hits them, and is immediately sliced into three equal pieces.
Leonard: Unless Superman matches her speed and decelerates.
Sheldon: In what space, sir, in what space? She's two feet above the ground. Frankly, if he really loved her, he'd let her hit the pavement. It would be a more merciful death.

Leonard: Come on! We have a combined IQ of 360 we should be able to figure out how to get into a stupid building.
*Two girls selling cookies ring every bell, the door opens*
Sheldon: What do you think their combined IQ is ?

Raj: I say we wait until he looks at us then laugh, like "Yes, you're a smart and strong competitor but we're also smart and strong and we have a reasonable chance of defeating you".

Sheldon: How often does one see a beloved fictional character come to life?
Wolowitz: Every year at ComiCon. Every day at Disneyland. You can hire Snow White to come to your house. Of course they prefer if you have a kid.

Leonard: Wow, Penny, you're on fire!
Penny: Yeah, so is Sheldon!

Leonard: Before you say anything, have you heard of Schrodinger's cat?
Penny: Actually, I've heard far too much about Schrodinger's cat.
Leonard: Good.
*Leonard and Penny kiss*
Penny: All right, the cat's alive. Let's go to dinner.

Sheldon: (On the phone) Howard, I'm sick.
Howard: (Hesitating, Imitating Mrs. Wolowitz) Howard's sleeping, this is his mother. Why are you calling at this ungodly hour?
Sheldon: I need soup!
Howard: (Imitating Mrs. Wolowitz) Then call your own mother.

Leonard: What makes you think she wouldn't have sex with me? I'm a male and she's a female.
Sheldon: Yes, but not of the same species.

Sheldon: I have a masters and two PhDs. I should not have to do this.

Leonard: (To Howard and Raj) Sheldon is at the Cheesecake Factory.
Leonard: (On the phone to Penny) Just tell him to go home.
Penny: Well, he won't leave. He says he's afraid he'll pass out on the bus and someone will harvest his organs.
Leonard: (to Howard & Raj) He is paranoid and he has established a nest.

Mary Cooper: I'm sorry, did I start that sentence with the words, "If it pleases your highness?"

Howard: Don't you think I should answer the engineering questions? I am an engineer.
Sheldon: By that logic I should answer all the anthropology questions because I'm a mammal.