Leonard: Wait, Alex, do you want to join us?
Sheldon: Alex, a moment. I need a word with Dr. Hofstadter.
Do you think it's appropriate for her to sit with us, given her station?
Leonard: Given her what?
Sheldon: If I've learned anything from British television shows on PBS, it's that servants dine down stairs with their own kind.
Leonard: What?
Sheldon: It's a kindness, Leonard. Otherwise, you're cruelly tempting them with a glimpse of a world that's just beyond their soot-stained fingertips.

Bernadette: How you doing, Howie? You feeling a little better?
Howard: Oh, a lot better, thanks. One sec. Listen close, I don't have a lot of time. I need you to go to my house. In my bedroom, you'll find a model rocket. I want you to take it and bring it back to your place.
Bernadette: Okay.
Howard: Step two, build a version roughly fourteen stories high. Fill it full of rocket fuel and come get me. I'll leave the door unlocked.
Bernadette: Howie, honey, maybe you should talk to someone, let them know you're having a little anxiety.
Howard: No, no, I'm fine. No anxiety. We should probably talk in code. From now on, frog is me, sandwich means you and lemon means rocket. So, come on, sandwich, build me a lemon 'cause froggy wants to come home.

Penny: Well, of course he's desirable. I mean, he's great. He's smart, he's sweet and, ooh, in the bedroom, whew, let me tell you he really tries.

Howard: Well, remember the Soyuz capsule they were sending to bring us home?
Bernadette: Uh huh.
Howard: It's delayed. We're gonna be here for at least another week. Maybe ten days. It's the Russians, so you don't know. They left dogs up here in the sixties.

Bernadette: You're going to be fine. You survived that Weight Watchers cruise with your mom. And they ran out of low-fat ice cream on day two. Just calm down and take a few deep breaths.

Amy: Sheldon told me he had a new assistant named Alex. He didn't mention that Alex was a girl.
Penny: Maybe he didn't notice.

Penny: She is not going to come on to Sheldon.
Amy: Oh, really? Look at this face. How can any woman spend eight hours a day alone with this face and not fall in love with it?
Penny: Well, for starters, at some point that face starts talking.

Penny: What are you doing?
Amy: Isn't it obvious? I'm spreading my scent to mark my territory.
Penny: Come on, Amy. That is not going to work.
Amy: Really? Because just before you became my best friend, I did this all over your apartment.

Howard: I really miss gravity. Can you drop something so I can watch it fall?
Bernadette: Really, you're serious? Okay.
Howard: Oh, baby, you're killing me.

Sheldon: Are you familiar with the Higgs boson?
Penny: Of course, it is - it's been in the news. And it's a very famous boson.
Sheldon: Nice try.

Penny: You really think there's some kind of scientific discovery in here?
Sheldon: Well, this box only covers my work through nursery school. There's a good deal more to come. I didn't really hit my academic stride until I cut out that time-suck known as playing outdoors.

Alex: Look, Dr. Cooper. I really want this position. It would be an incredible honor to work for a man of your brilliance.
Sheldon: Flattery will not get you this job, Ms. Jensen.
Alex: It's not flattery if it's the truth.
Sheldon: Oh, well, thank you. Welcome aboard.

Alex: I'm Alex, Dr. Cooper's new assistant.
Leonard: Ah, congratulations and may God have mercy on your soul. I'm Leonard.

Leonard: My dad was an anthropologist. The only father-son time he spent was with a 2,000-year-old skeleton of a Etruscan boy. I hated that kid.

Sheldon: I got the results back. Have you developed any of the following symptoms? A growing nose, or perhaps a warm sensation in the trouser region? Also known as full-blown liar, liar, pants on fire.