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.

Sheldon: Now remember, you were given powerful pain medication and a muscle relaxer, so don't operate heavy machinery, and try not to choke on your own drool. [goes to leave] Penny: Wait! You have to help me get into bed. [laughs] "Sheldon has to help me get into bed". Bet you thought I'd never say that!
Sheldon: Yes. Charmed. Your drug-addled candor knows no bounds. [helps Penny into bed]
Penny: You know people think you are this weird robot man who's so annoying all the time and you totally are. But then it's like that movie Wall-E at the end. You're so full of love and you can save a plant and get fat people out of their floaty chairs.
Sheldon: That's a fairly labored metaphor but I appreciate the sentiment behind it.

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.

Raj: With your American accent, everything you say sounds stupid.

Raj: If I could speak the language of rabbits, they would be amazed, and I would be their king.
Leonard: I hate my name. It has 'nerd' in it. 'Len. Nerd.'
Wolowitz: I lost my virginity to my cousin Jeanie.
Raj: I would be kind to my rabbit subjects. At first.