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.
Sheldon: Screwed.
Leonard: There you go.

Leonard: When we watch Frosty the Snowman, he roots for the sun.
Sheldon: Excuse me, but the sun is essential for all life on earth. Frosty is merely a bit of frozen, supernatural ephemera in a stolen hat. A crime, by the way, for which he is never brought to account.

Leonard: Well, it seems once again you're caught between a rock and a crazy place.
Sheldon: Oh, I hate when that happens.

Leonard: Well, it wasn't my fault.
Sheldon: The implication being that you somehow tripped and fell into her lady parts?

You call that a glowstick? [Pulls out his light saber and turns it on.] That is a glowstick!

Penny: Hi. Did Sheldon change the Wi-Fi password again?
Leonard: Yeah, it's "Penny already eats our food she can pay for Wi-Fi." No spaces.

Leonard: Why do I have to talk to Penny? She's not my girlfriend.
Sheldon: You invited her to lunch four years ago, everything about her is on you: you make it so!

Leonard: Why would you buy peppermint schnapps?
Penny: Because I like peppermint, and it's fun to say schnapps!

Sheldon: I can't seem to get in touch with Amy. I tried e-mail, video chat, tweeting her, posting on her Facebook wall,texting her, nothing.
Leonard: Did you try calling her on the telephone?
Sheldon: The telephone. You know, Leonard, in your own simple way, you may be the wisest of us all.

Raj: Woh, woh, woh! I don't want to speak to the FBI.
Leonard: Why not?
Raj: I'm brown and I talk funny.

Leonard: Too casual?
Sheldon: For an audience with the queen, yes. For an evening of passing a bottle of fortified wine around a flaming trash can, you look great.

Sheldon: How could you not find him?
Leonard: Because he's hard to find. If he was easy to find, the books would be called "There's Waldo."

TBBT Quotes

It's very simple. 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

Sheldon: Why do you have the Chinese character for "soup" tattooed on your right buttock?
Penny: It's not "soup," it's "courage."
Sheldon: No it isn't. But I suppose it does take courage to demonstrate that kind of commitment to soup.
Penny: How'd you see it? You said you wouldn't look.
Sheldon: Sorry. As I told you, the hero always peeks.