Leonard: You see, I used to be a jackass, but I stopped myself. I became a good guy. See, that's kind of my superpower. I'm like Captain Good Guy!
(Alice pushes him out, then slams door)
Leonard: It's okay. Did the right thing. *tightens his jacket* You idiot!

Leonard: What would you be if you were attached to another object by an inclined plane, wrapped helically around an axis?
Sheldon: Screwed?
Leonard: There you go.

Leonard: Penny, as a scientist, my job is to figure out why things happen. But I don't think I'll ever understand how someone like me could get to be with someone like you. You know maybe I don't need to understand it, I just need to be grateful. I love you, Penny.

Sheldon: This song is never going to stop. Have you ever dealt with something so relentlessly irritating?
Leonard: That's a trick question, right?

Leonard: More Halloween candy. Didn't you just buy a bunch of it yesterday?
Penny: Oh, yeah. That's gone. It's a rough month when Halloween and PMS hit at the same time.

Raj: (Talking to the snake) Let's go to the biology lab and find you some nice yummy mice.
Sheldon: I tried to scare an Indian with a snake. Come on, Cooper. You're better than this.

Sheldon: [jumps out of the sofa] Bazinga, punk. Now we're even!