Libby: What are you doing?
Sheldon: I need to use the bathroom, but it can get uncivilized in there.
Libby: Anyone in there now?
Sheldon: I don't know. I was afraid to find out.
Libby: Anybody in here? Go ahead. I'll stand guard.
Sheldon: Where have you been all my life?

Mary: Where were we?
Sheldon: Different kinds of maturity.
Mary: That's right. There's emotional maturity, physical maturity, all things that have nothing to do with being smart.
Sheldon: Are you suggesting I'm not emotionally mature?
Mary: I was hinting at it.

Tam: What are you doing?
Sheldon: I heard you could punch a hole in these and make them double-sided.
Tam: Then it would have more storage?
Sheldon: Yes, but I didn't pay for a double-sided floppy disk.
Tam: So?
Sheldon: So it's an ethical dilemma.
Tam: We have to take a shower in the locker room next period, and that's what you're worried about?
Sheldon: Actually, I have a bathing suit under my pants.

Sheldon: "Geologists lead a sedimentary lifestyle." Libby, that is a good one.

Sheldon: You're gonna be a geologist. That's fascinating. Why'd you choose that?
Libby: When I was a little girl, my grandparents took me to Carlsbad Caverns, and I was hooked.
Tam: Exploring caves, that is super cool.
Sheldon: Disagree. Dark, enclosed spaces are terrifying. I get scared putting on a sweatshirt.
Libby: Hmm.
Tam: I've seen it. Pretty entertaining.

Tam: So we eat in the library every day. You're welcome to join us.
Sheldon: It's much better than the cafeteria. It's quiet, and a lot less food gets thrown at us.

Sheldon: I think the best space shuttle name so far is Discovery.
Tam: What about Challenger?
Sheldon: Too in-your-face.
Libby: Atlantis?
Sheldon: A fictional island that couldn't stay afloat? I don't think so.
Tam: There's the Enterprise.
Sheldon: There is, and it's on Star Trek, where it belongs.

Mary: Hey. I want to talk to you.
Sheldon: Hold on. Let me bring this into the station so as not to disappoint my commuters. They'd like to get home to their families.

Libby: What do you want?
Sheldon: Would you like to have lunch with me and my friend?
Libby: Why?
Sheldon: Why else? So we can have a spirited conversation about geostatistics.
Libby: You really are as smart as everybody says.
Sheldon: My teeth are small, but my prefrontal cortex is enormous.

Libby: Do you know what you're going to major in in college?
Sheldon: I'm leaning towards quantum chromodynamics, but who knows? A few years ago, I would've said choo-choo trains.

Mary: So how was school today?
Georgie: Sheldon's got a girlfriend.
Missy: What?
Sheldon: That's not true.
Georgie: Oh, yes, it is. I seen him talking to her at school.
Meemaw: Sheldon Lee Cooper, you dog.
George: Is she cute?
Sheldon: Compared to what?

Mary: What grade is she in?
Sheldon: Eleventh.
George: An older woman. Nice.
Sheldon: Most everybody's older than me. Why is that nice?

George: Hang on. What did you think was gonna happen when we sent him to high school?
Mary: I don't know, that he'd learn stuff, and then, come back home and be my baby forever.
George: Mare, it's good for him. He may start college in a couple years, what happens then?
Mary: Off the top of my head, he and I share a dorm room.
George: You know I'd laugh at that if I didn't kind of believe you.

Libby: I don't think so.
Doug: I gotta pee.
Libby: That's your problem. Keep moving.

Libby: You know they're playing a space shuttle movie at the Museum of Natural Science. It's in IMAX.
Tam: I heard about that. The screen is supposed to be huge.
Libby: They also have a great geology exhibit.
Sheldon: Well, it's in Houston. How are we gonna get there?
Libby: I'll drive.
Tam: Oh, I would love to see a movie with you.
Sheldon: Don't you need to ask your parents first?
Tam: No, Sheldon, I don't.
Sheldon: But won't they worry where you are?
Tam: They'll be fine. Count me in.
Sheldon: Glad you're not my son.