Raj: I don't like bugs, okay? They freak me out.
Sheldon: Interesting. You're afraid of insects and women. Ladybugs must render you catatonic.
Zack: You know, I saw this great thing on the Discovery Channel. Turns out if you kill a starfish it'll just come back to life.
Sheldon: Was the starfish wearing boxer shorts? Because you might have been watching Nickelodeon.
Penny: So what do you say Sheldon, are we your X-men?
Sheldon: No, the X-men were named for the X in Charles Xavier. Since I am Sheldon Cooper, you will be, my C-men.
Penny: I always tear up when the Grinch's heart grows three sizes.
Sheldon: Tears seem appropriate. Enlargement of the heart muscle, or hypertrophic cardiomyopathy, is a serious disease which can lead to congestive heart failure.
Howard: Hope you don't mind, I told my girlfriend, Bernadette, she can join us for dinner.
Leonard: Sure, the more the merrier.
Sheldon: Wait, no. That's a false equivalency. More does not equal merry. If there was 2000 people in this apartment right now, would we be celebrating? No, we'd be suffocating.
Sheldon: Cause of Injury: Lack of Adhesive Ducks.
Leonard: You'll never guess what just happened.
Sheldon: You went out into the hallway, stumbled into an inter-dimensional portal which brought you 5,000 years into the future, which you took advantage of the advanced technology to build a time machine, and now you're back to bring us all with you to the year 7010, where we transported to work at the thinkatorium by telepathically controlled dolphins.
Sheldon: You know, in difficult times like this, I often turn to a force stronger than myself.
Amy: Religion?
Sheldon: Star Trek.
Sheldon: At my age do you know how I'm statistically most likely to die?
Leonard: At the hands of your room mate?
Sheldon: An accident.
Leonard: That's how I'm going to make it look
Leonard: Do you think we can outrun him?
Sheldon: I don't need to outrun him, I just need to outrun you.
Sheldon: Well, well, well, if it isn't Will Wheaton. The Green Goblin to my Spider-Man, the Pope Paul V to my Galileo, the Internet Explorer to my Firefox!
Sheldon: Good morning everyone and welcome to "Science and Society". I'm Dr. Sheldon Cooper, BS, MS, MA, PhD and ScD. OMG, right?
Sheldon: A neutron walks into a bar and asks how much for a drink. The bartender replies "for you, no charge".
Penny: No big deal. Not knowing is part of the fun!
Sheldon: (Imitating Penny) 'Not knowing is part of the fun.' Was that the motto of your community college?
Leonard: How could you just sit there and let them spy on me!?
Sheldon: They were very smart! They used my complete lack of interest in what you are doing.
Leonard: Relax, it's just a dirty sock.
Sheldon: How on earth can you say "dirty sock" and "relax" in the same sentence?
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.
Penny: Look, can we just forget about this extra stuff and can you just tell me what Leonard does?
Sheldon: Alright. Leonard is attempting to learn why subatomic particles move the way they do.
Penny: Really? That's it? Well, that doesn't sound so complicated.
Sheldon: It's not... it's why Leonard does it.
Sheldon: I'll watch the last 24 minutes of Doctor Who, although at this point it's more like Doctor Why Bother.
Sheldon: Given that Saint Valentine was a 3rd century Roman priest, who was stoned and beheaded, wouldn't a more appropriate celebration of the evening be taking one's steady gal to witness a brutal murder?
Leonard: Come on! We have a combined IQ of 360 we should be able to figure out how to get into a stupid building.
*Two girls selling cookies ring every bell, the door opens*
Sheldon: What do you think their combined IQ is?
Sheldon: So, you're saying this is a regulation deck?
Howard: I'm saying believe in magic, you muggle!
Raj: (Talking to the snake) Let's go to the biology lab and find you some nice yummy mice. *Raj leaves the room*
Sheldon: I tried to scare an Indian with a snake. Come on, Cooper. You're better than this.