"Penny: So, how've you been?
Sheldon: Well, my existence is a continuum, so I've been what I am at each point in the implied time period."
"Leonard: You are not Isaac Newton.
Sheldon: No, no, that's true. Gravity would have been apparent to me without the apple."
"Sheldon: This is the temperature you agreed to in the roommate agreement.
Leonard: Aw, screw the roommate agreement!
Sheldon: No, you don't screw the roommate agreement. The roommate agreement screws you."
"Leonard: Have you considered telling her your feelings?
Sheldon: Leonard, I'm a physicist, not a hippie.
Leonard: Well let me see if I can explain your situation using physics. What would you be if you were attached to another object by an incline plane, wrapped helicly around an axis.
Leonard: There you go."
"Penny: Can I ask you a question?
Sheldon: Given your community college education, I encourage you to ask as many as possible."
"Sheldon: You're asking me to use my superior intellect in a tawdry competition. Would you ask Picasso to play Pictionary? Would you ask Noah Webster to play Boggle? Would you ask Jacques Cousteau to play Go Fish?"
Sheldon: Your shoes are delightful. Where did you get them?
Sheldon: Bazinga, I don't care."
"Sheldon: I am uncomfortable having been included in your lie to Penny.
Leonard: What was I supposed to say?
Sheldon: You could have told her the truth.
Leonard: I could not have said that, it would have hurt her feelings.
Sheldon: Is that a relevant factor?
Sheldon: Then I suppose you could have agreed to go.
Leonard: What would I have said afterwards?
Sheldon: I would suggest something along the lines of "singing is neither an appropriate vocation nor avocation for you and if you disagree, I recommend you do a CAT scan to locate the tumor which is pressing on the cognitive processing center of your brain".
"Sheldon: What part of an inverse tangent approaching an asymptote don't you understand?"
"Sheldon: There's an economic concept known as a positional good in which an object is only valued by the possessor because it's not possessed by others. The term was coined in 1976 by economist Fred Hirsch to replace the more colloquial, but less precise "neener-neener"."
"Sheldon: Incidentally, one can get beaten up in school simply by referring to oneself as one."
"Sheldon: I'll have a diet Coke.
Penny: Can you please order a cocktail? I need to practice mixing drinks.
Sheldon: Fine... I'll have a virgin Cuba Libre.
Penny: That's... rum and Coke without the rum.
Sheldon: Yes, and would you make it diet?"
"Leonard: Sheldon, why is this letter in the trash?
Sheldon: Well, there's always the possibility that a trash can spontaneously formed around the letter, but Occam's Razor would suggest that someone threw it out."