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.

Raj: I don't like bugs, okay. They freak me out.
Sheldon: Interesting. You're afraid of insects and women. Ladybugs must render you catatonic.

Sheldon: Scissors cuts paper, paper covers rock, rock crushes lizard, lizard poisons Spock, Spock smashes scissors, scissors decapitates lizard, lizard eats paper, paper disproves Spock, Spock vaporizes rock, and as it always has, rock crushes scissors.

Sheldon: Why are you crying?
Penny: Because I'm stupid.
Sheldon: That's no reason to cry. One cries because one is sad. For example, I cry because others are stupid, and that makes me sad.

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.

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.