Amy: Sheldon, you've never worked in a lab like this before. You have no experience in the field of biology.
Sheldon: I have plenty of experience in biology. I bought a Tamagotchi in 1998. And it's still alive. Let's do this.

Mrs. Davis: Roots?
Sheldon: The tragic history of slavery in America. Fun for the whole family.
Mrs. Davis:: Why would you think this is an appropriate gift?
Sheldon: Umm. Well, you are black, right?

Sheldon: I appreciate your interest in the apartment. I just need to ask you a few standard questions.
Applicant: Sure.
Sheldon: It says here you're a chemist. Which element on the periodic table do you feel is too big for its britches?
Applicant: Is that supposed to be a joke?
Sheldon: Looks like argon's not the only one with an attitude problem.

Sheldon: Well now I know how it must have felt being mauled by that sex-crazed gorilla.

Sheldon: Oh stop it. I don't need to take this admiration from the likes of you people.

Penny: Aww, that's great. You're going to be an uncle. Uncle Sheldon.
Sheldon: No, I will be Uncle Dr. Cooper.

Raj: Yeah, okay, whatever it takes to keep you busy for a few hours.
Sheldon: Found one.
Raj: No, you didn't. There are millions of data points there.
Sheldon: But, look, an optical transient.
Raj: Yeah, maybe that is something. How did you find that?
Sheldon: It wasn't difficult. You know how when you see prime numbers, they appear red, but when they're twin primes, they're pink and smell like gasoline?
Raj: No.
Sheldon: Oh. I guess I'm a special boy. You know, sometimes when a boy is special, he gets a Fudgsicle. Which, by the way, tastes like the speed of light.

Amy: Listen, you and I are gonna be sharing a bed. You know, this is uncharted territory for both of us. How are you feeling about that?
Sheldon: Oh, excited, concerned, a little scared. All the same emotions I feel in line at Space Mountain.

Sheldon: If you want to blend in with Penny's friends, I'd think looking like an idiot would be the perfect camouflage.

Leonard: How long is he going to stay here?
Sheldon: He's a homeless drug addict, Leonard. Where's he going to go? Boy, you have a lot to learn about lying.

Penny: What if you asked for $20 million?
Sheldon: I'm sorry, I'm trying to do science, not hire Lady Gaga to come to my birthday.
Penny: Do you even know who Lady Gaga is?
Sheldon: Presumably, the wife of Lord Gaga.

Sheldon: Are you implying my girlfriend doesn't have any sexuality to exploit?
Raj: Yes.
Sheldon: Okay, because that was not clear.

Amy: When you told me I was going to be "losing my virginity", I didn't think you meant showing me Raiders of the Lost Ark for the first time.
Sheldon: My apologies. I chose my words poorly. I should have said you were about to have your world rocked on my couch.

Sheldon: I've been told that a bald refusal of an invitation is rude and one must instead offer up a polite excuse. So, I'd love to but unfortunately that sounds awful.

Sheldon: Wow, wow, wow, wow. Just because I love you, doesn't mean girls are allowed in my room.