Penny: You know, I believe in ghosts, too.
Leonard: Great.
Penny: And astrology.
Leonard: I know, and pyramid power and healing crystals.
Penny: Oh, no, no, no, crystals don’t work.
Leonard: Really, that’s the line? Psychics are real, but crystals are voodoo?
Penny: Oh, Voodoo is real. You don't want to mess with Voodoo.

Penny: Sheldon, did you have a Christmas tree?
Sheldon: Oh, yes. We had a tree, we had a manger, we had an inflatable Santa Claus with plastic reindeer on the front lawn. And to make things even more jolly, there were so many blinking lights on the house they induced neighborhood-wide seizures.

Sheldon: I made tea.
Leonard: I don't want tea.
Sheldon: I didn't make tea for you. This is my tea.
Leonard: Then why are you telling me?
Sheldon: It's a conversation starter.
Leonard: That's a lousy conversation starter.
Sheldon: Oh, is it? We're conversing. Checkmate.

Leonard: Howard, relax. I am not interested in your girlfriend.
Howard: I hope not. Because you don't wanna mess with me. *Gets in Leonard's face* I'm crazy.

Sheldon: Mom was right, hell is real.

Raj: We are from the Lollipop guild and we want you!

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.

Howard: So nice you could join me this evening, you're looking lovely as always.
Katee Sackhoff: Thanks Howard, always nice to be part of your masturbatory fantasies.

Sheldon: What are you talking about?
Leonard: The cultural paradigm in which people have sex after 3 dates.
Sheldon: I see. Now, are we talking date the social interaction or date the dried fruit?

Sheldon: (On helium) Kripke! I found the nozzle. I'm gonna kill you!

Sheldon: Biologically speaking, Howard is perfectly justified in seeking out the optimum mate for the propagation of his genetic line. Howard: Thank you, Sheldon. Sheldon: And whether that propagation is in the interest of humanity is, of course, an entirely different question.

Leonard: Ethyl alcohol inhibits electrical conduction in the nerve cells and stimulates re-uptake receptors of inhibitory neurotransmitters like gamma-amino butyric acid.

Penny: Honey, you don't have to thank me every time we have sex, sweetie.

Sheldon: Cause of Injury: Lack of Adhesive Ducks.

Sheldon: You keep in mind that my sharply-worded comments on Yelp.com recently took down a muffin store.