Sheldon: Oh, Leonard, I have something for you. Per our roommate agreement, this is your 24-hour notice that I will be having a non-related female spending two nights in our apartment.
Leonard: When you say non-related female, you still mean human, right?
Sheldon: Of course. Pets are banned under the roommate agreement, with the exception of service animals, such as seeing eye dogs and, one day, cybernetically enhanced helper monkeys.

Leonard: Why is a world-renowned scientist staying in our apartment instead of a hotel?
Sheldon: Well, she doesn't care for hotels. And who can blame here? Windows that don't open, multi-user linens, keys shaped like credit cards, as if one walks around with unassigned slots in one's wallet.

Sheldon: A word of warning. My guest is a noted physicist and the leading expert on quantum cosmology, so please try to avoid wasting her time with female jibber jabber.
Penny: Female jibber jabber?
Sheldon: Shoe sales, hair styles, mud masks, gossip about your friends Brad and Angelina.
Penny: Oh, they're not my friends.
Sheldon: I'm not surprised, considering the way you talk about them behind their backs.

Sheldon: In here you'll find emergency provisions. An eight-day supply of food and water, a crossbow, season two of Star Trek: The Original Series on a high-density flash drive.
Elizabeth: What if there's a disaster that destroys all the USB ports?
Sheldon: Then there's really no reason to live, is there?

Sheldon: Try to put yourself in my place. Imagine you're the sole human being living on a planet populated with nothing but dogs. And then it turns out there's another human being.
Howard: Hang on, are you saying the rest of us are dogs?
Sheldon: Okay. I can see you're going to take this the wrong way. Let me try again. Imagine you're the sole human being on a planet populated with nothing but chimps.
Howard: Get out of my lab.
Sheldon: Oh, now they're much smarter than dogs. Have you seen them on those bicycles?
Howard: Get out.
Sheldon: How about dolphins?

Sheldon: That's a lot of belt buckles.
Howard: Funny thing is, I have only one belt. Anyway, I'll get you started. Oh, by the way, the little marks that look like water spots, I tend to stand too close to the urinal, so what you're seeing there is splash back.
Sheldon: You make sissy on your belt buckles? Mee-Maw's forks never had that.

Amy: I need someone to accompany me to the wedding of Dr. Moranelli and Dr. Gustafson this Friday. They're kind of the Brad and Angelina of the primatology department.
Leonard: Wouldn't you rather bring Sheldon?
Amy: I would, but the last wedding we went to was a disaster. He behaved like a child the entire time.
Sheldon: Not my fault. You said there'd be other scientists there my age.

Sheldon: I've decided that I'm going to have Mr. Lee sign my copy of this month's Batman.
Howard: That's crazy. Stan Lee had nothing to do with Batman.
Sheldon: Yes, which is why no one else will ask him to sign one, and I will be the possessor of a unique, albeit confusing, artefact, which will set me apart from the hoi polloi of comic book fandom

Raj: They get girlfriends and they just abandon us?
Sheldon: It is great, isn't it? We have a wonderful evening ahead of us.

Raj: Come on, Sheldon, the world is filled with people doing things outside. Let's go outside. Outside is good.
Sheldon: If outside is so good, why has mankind spent thousands of years trying to perfect inside?

Sheldon: I would like a root beer float.
Raj: Sheldon, they don't have ice cream.
Sheldon: They don't? Well, apparently these people and I differ greatly on the definition of party.

Leonard: See, Howard's just as good a dungeon master as I am.
Sheldon: As good? You just got pantsed in the schoolyard, four eyes.

Penny: The building manager's showing an apartment downstairs, and I haven't paid my rent.
Sheldon: Oh, I see. Penny, I'm not sure I'm comfortable harboring a fugitive from the 2311 North Los Robles Corporation.

Penny: Wow, you got a lot of money in there.
Sheldon: That's why it's guarded by snakes.

Sheldon: I see no large upcoming expenditures unless they develop an affordable technology to fuse my skeleton with admantium like Wolverine.
Penny: Are they working on that?
Sheldon: I sincerely hope so.