The Extract Obliteration - S6-E6
Stephen Hawking: Do you like brain teasers?
Sheldon Cooper: Oh, I love brain teasers.
Stephen Hawking: What do Sheldon Cooper and a black hole have in common? They both suck. Neener, neener.
The Staircase Implementation - S3-E22
Leonard: Oh, screw the roommate agreement!
Sheldon: No, you don't screw the roommate agreement! The roommate agreement screws you!
The Big Bran Hypothesis - S1-E2
Sheldon: Oh Gravity, thou art a heartless bitch.
The Desperation Emanation - S4-E5
Leonard: What about you, Stuart? You have a girlfriend yet?
Stuart: Oh, yeah. Yeah. I met her at Comic-Con, the one place in the world where saying I own a comic book store is an actual pickup line.
The Bat Jar Conjecture - S1-E13
Sheldon: At this point, I should inform you that I intend to form my own team and destroy the very bonds that bind your very matter together and reduce the resulting particulate chaos to tears!
Leonard: Thanks for the heads up.
Sheldon: You're welcome. [Turns to leave.] One more thing,
Leonard: Yes?
Sheldon: It's on, bitch.
The Lizard-Spock Expansion - S2-E8
Sheldon: What happened?
Leonard: Howard's at the Mars Rover lab. He says he's in trouble. Defcon 5.
Sheldon: Defcon 5? Well, there's no need to rush.
Leonard: What?
Sheldon: Defcon 5 means no danger. Defcon 1 is a crisis.
Leonard: How can 5 not be worse than 1?
Raj: Yeah, Star Trek V, worse than I.
Sheldon: Okay, first of all, that's a comparison of quality, not intensity. Secondly, Star Trek I is orders-of-magnitude worse than Star Trek V.
Raj: Are you joking? Star Trek V is the standard against which all badness is measured.
Sheldon: No, no, no. Star Trek V has specific failures in writing and direction, while Star Trek I fails across the board, art direction, costuming, music, sound editing.
Leonard: Can we just forget I said Defcon and go?
Raj: Star Trek V!
Sheldon: All right, will you at least stipulate that Star Trek IV: The Voyage Home is in-arguably the best?
Raj: I have three words for you. Wrath of Khan.
The Lizard-Spock Expansion - S2-E8
Sheldon: I'm sorry, but I'm not going to watch the Clone Wars TV series until I've seen the Clone Wars movie. I prefer to let George Lucas disappoint me in the order he intended.
The Agreement Dissection - S4-E21
Sheldon: You may have gone to Cambridge, but I am an honorary graduate of Starfleet Academy.
Sheldon: Every Saturday morning since we've lived in this apartment, I have awakened at 6:15, poured myself a bowl of cereal, added a quarter cup of 2% milk, sat on that end of that couch, turned on BBC America and watched Doctor Who.
Leonard: Penny's still sleeping.
[Sheldon stares at Penny for some time.]
Sheldon: Every Saturday since we've lived in this apartment.
The White Asparagus Triangulation - S2-E9
[Sheldon points to a computer.]
Sheldon: Tell me what you see here.
Leonard: The blunt instrument that will be the focus of my murder trial?
Sheldon: You participate in the mass cultural delusion that the sun's apparent position relative to arbitrarily defined constellations at the time of your birth somehow effects your personality.
Sheldon: I'm not crazy. My mother had me tested.
The Lizard-Spock Expansion - S2-E8
Howard Wolowitz: If it's "creepy" to use the Internet, military satellites, and robot aircraft to find a house full of gorgeous young models so I can drop in on them unexpected, then FINE, I'm "creepy."
The Vacation Solution - S5-E16
Howard: I'm not signing a pre-nup.
Penny: Alright, Howard Wolowitz, listen up. You sign anything she puts in front of you because you are the luckiest man alive. If you let her go, there is no way you will be able to find anyone else. Speaking on behalf of all women, it is not going to happen, we had a meeting!
Chosen answer: It does. The variable cleanliness of the cab and the habit of taxi drivers to engage customers in small talk would be too much for Sheldon to handle, and not an option for him.
Captain Defenestrator