Bernadette: Oh, I take pacts very seriously. One time at my lab, a petri dish of genetically modified super-virus went missing. That day we made a pinky swear never to admit we crossed Ebola with the common cold.
Howard: Why the hell would you cross Ebola with the common cold?
Bernadette: We never did. That would be a terrible, terrible thing.

Mrs. Wolowitz Howard, get the door.
Howard: Why can't you get it?
Mrs. Wolowitz You know I'm doing a bowel cleanse for my colonoscopy. I'm like an upside-down volcano here.

*Knock, Knock*
Leonard: Who is it?
Amy: Amy Farrah Fowler.
Sheldon: Darn, she found me.
Leonard: She's been here before.
Sheldon: The only flaw in an otherwise perfect plan. Now get my back, Jack.
Leonard: What do you want me to do?
Sheldon: Tell her I'm not here.
Leonard: Where are you?
Sheldon: I don't know. You'll have to devise a scenario that plausibly explains my absence keeping in mind that the key to a good lie lies in the details.
*Later, Leonard answers the door to Amy*
Leonard: Hi, Amy. Sheldon's not here.
Amy: All right.
Sheldon (to Leonard): Way to go on the details.

Sheldon: Amy, I find myself wondering if we should actually engage in coitus at least one time in our relationship. Bazinga! Bedtime. Please show yourself out.

Leonard: What about you, Stuart? Do 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 pick-up line.
Leonard: Oh, well, good for you.
Stuart: Not really, she's horrible. When she wants to have sex, she puts on her plus-size Wonder Woman costume and shouts, "Who wants to take a ride in my invisible plane?"
Leonard:Why don't you just break up with her.
Stuart: Heh, no, I can't.
Leonard: Why not?
Stuart: Because then I'd be alone. Like you.

Leonard: So you're still just texting and emailing? You don't feel any need to hang out with her, you know, be in the same room?
Sheldon: Leonard, you are my best friend. I've known you for seven years, and I can barely tolerate sitting on the couch with you. Imagine my attitude regarding prolonged physical proximity to Amy Farrah Fowler.

Sheldon: I sense judgment on your part.
Leonard: No, no. Maybe a little.
Sheldon: May I suggest that your criticism is based on jealousy.
Leonard: Jealousy? What do I have to be jealous of?
Sheldon: I have a functioning and satisfying relationship with a female. You have none.
Leonard: Oh, right. That.
Sheldon: Jealousy is an ugly green-eyed monster, not unlike the Hulk, who, by the way, also has a girlfriend. In this iteration, Jennifer Connelly, whom you may recall as the girlfriend of Russell Crowe in A Beautiful Mind, a feel-good romp if there ever was one.
Leonard: I'm not jealous.
Sheldon: Hurgh! Leonard not jealous.

Sheldon: What makes you chuckle, Leonard?
Leonard: Hmm, recently? Not much.
Sheldon: Is it because of the conflict that arises from your desperate need to pair-bond with a woman, and the apparent collective decision of all womankind to deny you that opportunity?
Leonard: Um, shut up.

Sheldon: You know, when my grandfather died, and Meemaw was alone, my mom arranged for her to visit a center three times a week where she could socialize with other lonely people. It's very nice. They discuss current events, play bridge, get a hot meal.
Leonard: That sounds lovely.
Sheldon: It is if you like bridge. Do you like bridge, Leonard?
Leonard: Sheldon, I'm just not dating someone right now. I don't need to go to a senior center.
Sheldon: Meemaw resisted at first, but now she loves it.
Leonard: Fine. If I don't meet someone soon, you can put me in a home.
Sheldon: It's not a home. It's a senior center. We'd never put Meemaw in a home!

Howard: (Cell phone rings) Excuse me. That's my girlfriend, Bernadette. I assigned her her own ringtone, Bernadette by The Four Tops. Hello, Bernadette.
Raj: When I call him, his phone plays Brown Eyed Girl. Which, now that I think about it, is not so good.

Sheldon: Leonard? Are you sleeping?
Leonard: No.
Sheldon: Are you ill?
Leonard: No.
Sheldon: Are you still depressed because you're alone, and no one loves you?
Leonard: I don't know. Maybe.
Sheldon: I want you to know that I'm genuinely concerned about your well-being.
Leonard: Thank you.
Sheldon: You're welcome. But it's still no reason to have your feet in my spot.

Amy: (via a webcam) May I offer an observation?
Leonard: What the hell? How long has she been here?
Sheldon: Since we got home from the comic bookstore.
Leonard: That was two hours ago.
Sheldon: As per your suggestion, we're hanging out. Quite frankly, I don't see what all the hoopla's about.

Amy: From a neurobiological standpoint, Leonard, you may be alone because your psychological state is causing an actual pheromone-based stink of desperation.

Amy: I understand that some people find mates in social gathering places such as bars or taverns. Have you tried a bar or tavern?
Leonard: No, I'm not gonna try to pick up a woman in a bar.
Sheldon: Wise decision. You see, Amy, success at a bar is based on classic male attributes such as height, strength, attractiveness, the ability to hold one's liquor and throw darts, separately or together. Leonard has none of these attributes, right, Leonard?
Leonard: Right.

Leonard: Look, she obviously wants to take your relationship to the next level.
Sheldon: I don't want the next level. I like this level. Fix it for me!
Leonard: Me? Well, how am I supposed to fix it?
Sheldon: Simple! You want a girlfriend, Amy wants to be someone's girlfriend. Take her off my hands. I give you my blessing.
Leonard: That is insane.
Sheldon: You're right. It would never work. Amy finds you tedious.