Leonard: What are you doing in there?
Sheldon: I'm making hydrogen sulphide and ammonia gas. Just a little experiment in pest control.
Raj: It's not gonna work, dude. I grew up in India, an entire subcontinent where cows walk in the street, and nobody has ever had a solid bowel movement.
Sheldon: Well, we'll just see how long you can hold out.
Raj: Well, we'll just see how your noxious gas fares against my cinnamon-apple-scented aroma therapy candles.
Leonard: Didn't you say you're making hydrogen sulphide gas?
Sheldon: Yes.
Leonard: Isn't that flammable?
Sheldon: Highly. Oh, dear. [explosion]

Leonard: Oh, who am I kidding? I can't go through with this, you need to call her and cancel.
Sheldon: Me?
Leonard: Yes.
Sheldon: What should I tell her?
Leonard: I don't know. Tell her I'm sick.
Sheldon: Okay.
Leonard: Not the kind of illness that will make her want to come over and take care of me, but nothing so critical that she'll feel uncomfortable going out with me in the future if I want to try this again.
Sheldon: Got it. So I'm assuming nothing venereal. I'll just tell her that you had a routine colonoscopy and haven't quite bounced back.

Sheldon: I've been dreaming about going to the Large Hadron Collider since I was nine years old.
Leonard: Yeah, well, I've been dreaming about spending Valentine's Day with a girl since I was six.
Sheldon: Shame on you! That's no dream for a scientist.

Leonard: Raj, no, it's a trap. They're flanking us!
Raj: Oooh, he's got me.
Howard: Sheldon, he's got Raj. Use your sleep spell. Sheldon! Sheldon!
Sheldon: I've got the Sword of Azeroth!
Leonard: Forget the sword, Sheldon, help Raj.
Sheldon: There is no more Sheldon. I am the Swordmaster!

Raj: I'm telling you, if xenon emits ultraviolet light, then those dark matter discoveries must be wrong.
Sheldon: Yes, well, if we lived in a world where slow-moving xenon produced light, then you'd be correct. Also, pigs would fly, my derrire would produce cotton candy, and The Phantom Menace would be a timeless classic.

Sheldon: Aquaman? This isn't a gag gift, Stuart.

Amy: Hey, good news. They're inviting several Nobel Laureates to our reception.
Sheldon: Oh, great, like who?
Amy: Uh, Makoto Kobayashi.
Sheldon: Ooh.
Amy: What?
Sheldon: Well, I may have been less than kind to him about his Nobel Prize win.
Amy: Why?
Sheldon: I was jealous, angry and new to Twitter. It was a dangerous combination.
Amy: Okay, so scratch Kobayashi.

Penny: (On the phone) Mrs. Cooper, hey, it's Penny. Yeah, I think I broke your son. Hey, hold on. Talk to your mother.
Sheldon: Mommy, I love you. Don't let Spock take me to the future!

Sheldon: Wait a minute! You're not going to do anything?
Police Officer: Mr. Cooper, theres nothing-
Sheldon: Doctor Cooper.
Police Officer: Seriously?
Leonard: Not the kind with access to drugs.
Police Officer: Fine. Dr. Cooper. I'm sorry for your loss, but the Pasadena Police Department doesn't have jurisdiction in Pandora.
Sheldon: That's from Avatar. World of Warcraft takes place in Azeroth. Goodness gracious, how are you allowed to carry a gun?

Sheldon: You just lied to Penny.
Leonard: Yes, I did.
Sheldon: And you did it so casually. No rapid breathing, no increase in perspiration.
Leonard: So?
Sheldon: So, lack of physiological response while lying is a characteristic of a violent sociopath.
Leonard: Sheldon, are you worried about your safety?
Sheldon: No. I imagine if you were going to kill me, you'd have done it a long time ago.

Sheldon: Pick a card, Sheldon. Now look at it and put it back in the deck. Now do you remember your card? Of course I do, I have an eidetic memory.

Sheldon: Danger! Danger!

Sheldon: Yes, hello. This is Dr. Sheldon Cooper. Yeah, I'm at 2311 North Robles Avenue. Yeah, I'd like to report a dangerous wild animal. A blue jay. I'm sorry, this is Animal Control. I don't understand the laughter. No, the bird is not in my home. If he was in my home, I obviously would have called 911. Sir, I have no doubt that there are things that you're frightened of. Being stuck in a dead-end public service job? Or your wife stepping out on you because you're stuck in a dead-end public service job? Or spiders? Don't you think I tried making cat noises?

Sheldon: The horror!
Penny: Sheldon, I'm sure it's going to be fine.
Sheldon: No, it's not going to be fine. Change is never fine. They say it is, but it's not.

Penny: This isn't fair to you, Leonard. I'm sorry. *runs off*
Sheldon: Penny, wait, come back. I'll get you ice cream!