Leonard: That's great news about you and Bernadette [getting back together]!
Howard: Yeah, I think I'm going to take her to miniature golf.
Leonard: Oh, well, I guess for you guys, that's like regular golf.
Howard: Short jokes, really? You're like a quarter of an inch taller than me!
Leonard: Yeah, and don't you forget it!

Leonard: What am I supposed to do, pretend I believe something I don't whenever I'm with Penny?
Howard: Hey I'm sure Penny fakes all kinds of things when she's with you.
Leonard: Do me a favor: lean over and put your head right here [in front of a laser he'd been using to fry action figures].
Howard: Let me show you another way to look at this. [Draws a large box on a dry-erase board] Here we have the universe of all women. [Draws one large circle inside the box] These are the ones you want to sleep with. [Draws an equal-size circle slightly intersecting the first] These are the women who believe exactly what you believe. [Draws a very small circle at bottom of the intersection] These are the women who would be willing to sleep with you. Right there at the little triple intersection is your ideal mate. Odds are she's a short physicist with low self-esteem who lives in a government research facility in China.
Leonard: What's your point? In order to keep having a sexual relationship with Penny, I have to give up everything I believe in, my intellectual integrity, the very nature of who I am? I can't do that, Howard.
Howard: I respect that. [takes Leonard's hand and dots his palm with the marker]
Leonard: What is that?
Howard: Your new girlfriend. Have fun tonight.

Leonard: What did Penny mean, "you'd make a cute couple"?
Sheldon: Well, I assume she meant that the two of you together would constitute a couple that others might consider cute. An alternate, though somewhat less likely interpretation is that you could manufacture one. As in, "Oh, look, Leonard and Leslie made Mr. and Mrs. Goldfarb! Aren't they adorable?"
Leonard: If Penny didn't know that Leslie had already turned me down, then that would unambiguously mean that she, Penny, thought I should ask her, Leslie, out, indicating that she, Penny, had no interest in me asking her, Penny, out; but because she did know that I had asked Leslie out, and that she, Leslie, had turned me down, then she, Penny, could be offering me consolation - "That's too bad, you would have made a cute couple..." - while thinking, "good, Leonard remains available."
Sheldon: You're a lucky man, Leonard.
Leonard: How so?
Sheldon: You're talking to one of the three men in the Western Hemisphere capable of following that train of thought.
Leonard: Well, what do you think?
Sheldon: I said I could follow it, I didn't say I cared.

Leonard: You'll never guess what just happened!
Sheldon: You went out in the hallway, stumbled into an interdimensional portal which brought you 5,000 years into the future where 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 are transported to work at the thinkatorium by telepathically controlled flying dolphins?
Leonard: No.
Sheldon: [Genuinely dissappointed] Aw.
Leonard: Penny kissed me.
Sheldon: Well, who would ever guess that?

Leslie: Hello, Sheldon.
Sheldon: [looks terrified] Leslie Winkle!
Leslie: Yeah, Leslie Winkle! The answer to the question, "Who made Sheldon Cooper cry like a little girl?".
Sheldon: Yes, well, I'm polymerized tree sap and you're an inorganic adhesive, so whatever verbal projectile you launch in my direction is reflected off of me, returns on its original trajectory and adheres to you.
Leslie: [sarcastically] Ooooh...ouch.

Mary Cooper: [Regarding Sheldon and Amy] You have any idea what's going on with those two?
Leonard: It's kind of like the Loch Ness monster. Maybe there's something there, maybe there isn't, we'll probably never know. But sometimes it's fun to creep yourself out thinking about it!

Mrs. Cooper: [in trying to get Sheldon to go apologize to his boss Dr. Gablehauzer] Now listen here, Sheldon, I've been telling you since you were five years old, it's okay to be smarter than everyone else, but you can't go around pointing it out!
Sheldon: Why?
Mrs. Cooper: [sternly] Because other people don't like it!! Remember all the ass-kickings you used to get from the neighbor kids? Are you ready? Get your shoes, shirt and let's shove off!
Sheldon: [in a defeated tone of voice] There wouldn't have been any ass-kickings if that stupid death-ray would've worked.

Mrs. Wolowitz: [as Howard is unlocking the front door] Who's there!? Are you a sex criminal!?
Howard: Sex criminals don't have keys, Ma! [goes inside]
Mrs. Wolowitz: Where were you so late!?
Howard: I was out with Bernadette!
Mrs. Wolowitz: I know what that means! I watch Dr. Phil! [short pause] I hope to God you used a condom!
Howard: I'm not having this conversation with you, Ma!
Mrs. Wolowitz: God forbid you get one of those new fancy sex diseases!
Howard: Nobody has a disease!
Mrs. Wolowitz: I hope not! I share a toilet with you! Is that what you want!? To give your mother herbies!?
Howard: That's it! I don't have to take this! [comes back outside, yelling at the front door] And good luck with your eyebrows in the morning!
[He starts to leave, then goes back to the door and unlocks it again]
Mrs. Wolowitz: Who's there!? Are you a sex criminal!?
Howard: [going back inside] Still leaving; I just forgot my Claritin!

Penny: [about going with the others to a science conference including a spa treatment] Boy, this is great. I haven't had a vacation in ages!
Sheldon: In order to take a vacation, one first has to work.
Penny: You know, for a smart guy, you really seem to have a hard time grasping the concept "Don't piss off the people who handle the things you eat". [leaves]
Amy: That does seem to be a valid principle.
Sheldon: [waves her off] I trust Penny will adhere to the official California Restaurant Worker's Solemn Oath of Ethics and Cleanliness.
Amy: I don't believe there's any such thing.
Sheldon: [to Leonard] You lied to me?

Penny: [after Zack leaves] You know, for a bunch of guys who claim to have spent a lot of their life being bullied, you can be real jerks. Shame on all of you.
Raj: [after Penny closes the door] What the hell did I do?
Penny: [opening door back up] You laughed. [Raj immediately shuts up]

Penny: [at the restaurant] What are you doing here?
Sheldon: A reasonable question. I asked myself, "What is the most mind-numbing, pedestrian job conceivable?" and three answers came to mind: tollbooth attendant, Apple Store genius, and what Penny does. Now, since I don't like touching other people's coins, and I refuse to contribute to the devaluation of the word "genius", here I am.
Penny: So that's it? You just walked in and they hired you just like that?
Sheldon: Oh, heavens, no! Since I don't have to be paid, I didn't have to be hired. I just walked in, picked up a tray, and started working for the Man.

Penny: [going through a box to find Sheldon's USB] Okay, I've got a box, but there's no key in here. Just letters.
Sheldon: [edgy] That's the wrong box. Put it back.
Penny: Oh, Sheldon, are these letters from your grandmother?
Sheldon: Don't read those letters!
Penny: Oh look! She calls you Moon Pie! That is so cute!
Sheldon: PUT DOWN THE LETTERS!

Penny: [on phone] How about this: you keep him there a little longer, and when you get to the party, I'll point out which of my friends are easy.
Howard: [long pause] Don't toy with me, woman.
Penny: I've got a hot former fat girl with no self-esteem, I got a girl who punishes her father by sleeping around, and an alcoholic who's two tequila shots away from letting you wear her like a hat.
Howard: Thy will be done. [Hangs up, takes out granola bar with peanuts, to which he is allergic, and looks to his crotch] I'm doing this for you, little buddy.

Penny: [sitting on Sheldon's spot, starts to move when she sees him] Hey, sorry Sheldon, I'll move.
Sheldon: [does not seem bothered by Penny] Why? My spot, your spot, what difference does it make?
[Penny and Leonard frown at him]
Penny: Okay, what just happened?
Leonard: I don't know... Between you playing chess like Bobby Fischer, and Sheldon being okay with you sitting in his spot... I'm guessing someone went back in time, stepped on a bug and changed the course of human events.

Penny: [Talking about screenplay writer in bar] No, I'm talking to him because he's cute.
Leonard: Come on, he's not that cute.
Penny: Yes he is, with his dorky t-shirt and his little hipster glasses.
Leonard: [long pause] I wear dorky t-shirts and glasses.
Penny: Yeah, but when you're tall and have great cheekbones, you're doing it ironically.