Sheldon: Pick a card, Sheldon. Now look at it and put it back in the deck. Now do you remember your card? Of course I do, I have an eidetic memory.

Sheldon: That is my spot. In an ever-changing world, it is a single point of consistency. If my life were expressed as a function on a four-dimensional Cartesian coordinate system, that spot at the moment I first sat on it would be zero-zero-zero-zero.

Amy: Have I ever told you you're like a sexy praying mantis?
Sheldon: Every time you drink alcohol.

Howard: Sheldon, why do you have all these unopened paychecks in your desk?
Sheldon: Because most of the things I'm planning to buy haven't been invented yet.
Howard: But there must be thousands of dollars here. Why don't you put it in the bank?
Sheldon: I don't trust banks. I believe that when the robots rise up, ATMs will lead the charge.

Raj: He'll have a Shirley Temple.
Sheldon: And don't be chintzy with the Shirley.

Leonard: You know, some people might say that it's great that we're trying to make things work long distance. They'd say things like, love is stronger than the miles between you.
Sheldon: When I rise to power, those people will be sterilized.

Sheldon: My expenses account for 46.9% of my after-tax income. The rest is divvied up between a small savings account, this deceptive container of peanut brittle, and the hollowed-out buttocks of a superhero action figure who shall remain nameless for his own protection. Or her own protection.

Penny: I'll pay you back as soon as I can.
Sheldon: Of course you will. It's impossible to pay me back sooner than you can. Assuming you subscribe to a linear understanding of time and causality.

Leonard: I grew up in a house full of crazy academics. Instead of leaving Santa milk and cookies, we had to leave him a research paper. And in the morning, you could tell he'd been there because the paper would be graded.
Sheldon: No wonder you love Christmas. That sounds amazing.
Leonard: It wasn't amazing. I got a C- four years in a row.
Sheldon: Yeah, I'm familiar with your work. C-minus was your gift.

Leonard: It must be hell inside your head.
Sheldon: At times.

Sheldon: Coins lodged in body parts is not a source of amusement. When I was five, Billy Sparks put a Mexican peso up my nose.
Howard: How is that not amusing?
Sheldon: It's still there. Takes me forty-fives minutes to get through airport security.

Alex: Well, I know she loves playing the harp, so I found this beautiful music box that plays one of her favorite songs.
Sheldon: Now, Amy already has a real harp and it can play any song. What are you trying to pull here?

Alex: I know she's a fan of The Canterbury Tales. So I found this cool map that illustrates the characters' journey through England. I thought we could put it in a really nice frame.
Sheldon: But she's got Google Maps on her phone.
Alex: I don't know how to respond to that.

Sheldon: This is the most thoughtful gift that anyone's ever given me. And that's including an amazing gift that I gave myself earlier today.

Amy: Well, the first thing that comes to mind is isolating the part of your brain where the memory is stored and destroying it with a laser.
Sheldon: Hmm, no. One slip of the hand and suddenly I'm sitting in the Engineering Department, building doodads with Wolowitz.