Sheldon: I'll go for two hundred, that time machine stays right where it is.
Raj: Three hundred, and I'll throw in my original 1979 Mattel Millenium Falcon with real light speed sound effects.
Leonard: No, no more toys or action figures or props or replicas or costumes or robots or Darth Vader voice changers, I'm getting rid of all of it.
Howard: You can't do that. Look what you've created here, it's like nerdvana.

Howard: You know, I'm really glad you decided to learn Mandarin.
Sheldon: Why?
Howard: Once you're fluent, you'll have a billion more people to annoy instead of me.

Bernadette: Maybe we should get one of those machines to help her up the stairs.
Howard: You mean a forklift?

Sheldon: Sheldon Cooper does not cry.
Howard: That's true, you'd rust.

Sheldon: Are you upset about something?
Leonard: What was your first clue?
Sheldon: Well, it was a number of things. First, the late hour, then you demeanor seems very low energy, plus your irritability.
Leonard: Yes, I'm upset!
Sheldon: Oh. I don't usually pick up on those things. Good for me.
Leonard: Yeah, good for you.
Sheldon: (walks away and then turns back) Oh, wait. Did you want to talk about what's bothering you?
Leonard: I don't know. Maybe.
Sheldon: Wow! I'm on fire tonight.

Leonard: Can I go back and prevent you from explaining that to me?
Sheldon: Same paradox. If you were to travel back in time and, say, knock me unconscious, you would not then have the conversation that irritated you, motivating you to go back and knock me unconscious.
Leonard: What if I knock you unconscious now?
Sheldon: It won't change the past.
Leonard: But it'd make the present so much nicer.

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!