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 Big Bran Hypothesis - S1-E2
Sheldon: Oh Gravity, thou art a heartless bitch.
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 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 Agreement Dissection - S4-E21
Sheldon: You may have gone to Cambridge, but I am an honorary graduate of Starfleet Academy.
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.
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!
Sheldon: I was analyzing our lie and I believe we're in danger of Penny seeing through the ruse.
Leonard: How?
Sheldon: Simple: If she were to log on to SoCal physics group.org forward slash activities forward slash other, scroll down to seminars, download the PDF schedule, and look for the seminar on molecular positronium, well then, bippity boppity boo, our pants are metaphorically on fire!
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