Leonard: What are you doing?
Sheldon: Playing the theremin.
Leonard: No. I mean, what are you doing with a theremin?
Sheldon: Playing it.

Sheldon: Raj, where do you stand on the anthropic principle?
Raj: I'm all for it.
Sheldon: Attaboy.
Leonard: Well, hang on. Why do you believe that he knows what it is and I don't?
Sheldon: Oh, Leonard. Let's not take a saw to the branch we're sitting on, shall we?

Raj: I need a hug.
Sheldon: Sorry, I have company.
Raj: Come on, Sheldon, open the door.
Sheldon: I don't want to hug you.
Raj: I don't want to hug you, either. I was just feeling blue.
Sheldon: Blue, as in depressed?
Raj: Well, not so much depressed as lonely.
Sheldon: I don't know what color lonely is.

Raj: Sheldon, listen to me. I have a big decision to make, and I'm scared.
Sheldon: Yellow. Go ahead.
Raj: A friend at the School of Pharmacology gave me these new pills they're testing. He says it's the next big thing for social anxiety disorder.
Sheldon: Fascinating. What's in it?
Raj: I'm not sure. Some sort of beta-blocker attached to a molecule extracted from the urine of cows.
Sheldon: I like cows.
Raj: That's not the point.
Sheldon: It was its own point. Go on.
Raj: I'm a scientist. My ability to think is my bread and butter. I'm afraid if I take this, I might lose that special, unique something that makes me so successful in my field.
Sheldon: Rajesh, I've had the privilege of working alongside you for many years. My recommendation is that you gobble these up like Tic Tacs.

Sheldon: You know, the more I think about it, the mobster sauce couldn't possibly contain chunks of mobster.
Leonard: And why is that?
Sheldon: It was listed under seafood.
Leonard: What if they were mobsters who slept with the fishes?
Sheldon: Leonard, are we having a serious conversation or not?

Sheldon: Wonderful security system if we're attacked by a school of tuna.
Howard: Don't worry, the net's going to be electrified. Picture her on the floor, spasming uncontrollably.
Sheldon: Better.

Sheldon: As is the tradition, I have prepared a series of disrespectful jokes which generate humor at Howard's expense. Prepare to have your ribs tickled.
Howard, I always thought you'd be the last one of us to ever get married, because you are so short and unappealing. Am I right?
Let's see here. Oh, seriously though, Howard, you're actually one of the most intelligent people I know. And that's a zinger, because you're not.
I've always thought that you'd make someone a fine husband someday. Assuming you'd be able to get the parts, and develop the engineering skills to assemble them, which I don't see as likely. Ha-cha!
Okay, let me see here. Okay, kidding aside, Howard, you are a good friend. And I wish you nothing but happiness. Bazinga, I don't!
Leonard: Sheldon...
Sheldon: Double-zinga! I do!
Good luck following that.

Leonard: Sheldon, it's not a great time. What do you want?
Sheldon: (on the phone in the apartment) Hello to you, too. I'm sorry, but this is important.
Leonard: What is it?
Sheldon: Back to the Future II was in the Back to the Future III case, and Back to the Future III was, get this, in the Back to the Future II case.
Leonard: So?
Sheldon: So, did you do that, or am I in the house with an intruder?

Penny: What's the matter?
Sheldon: Um, well, I was worried that you might be missing Leonard. And that might be causing you to have bad dreams, like the kind you'd get if you watched Clash of the Titans right before you went to bed.
Penny: Sweetie, did you have a bad dream?
Sheldon: To be honest, I did.
Penny: Aww.
Sheldon: Back to the Future II was in the Back to the Future III case. Leonard did it.

Sheldon: Dear Lord, you're an astronomer. Although you may have earthly woes, get your mind back on the stars. Gee, even the lowly dung beetle chooses to plot its course by using the Milky Way.
Raj: Is that true?
Sheldon: Everything I say is true. Now, of course, the dung beetle also enjoys eating feces, living in feces and making little balls out of feces, so, you know, pick and choose which aspects of its lifestyle you want to embrace.

Penny: Why don't you just admit you only want to play this game because you always play it with Leonard and you miss him?
Sheldon: You overestimate his significance in my life. Do I miss how he makes a face on my toaster waffle with syrup? No. Do I miss the way he fixes the zipper on my jacket when it gets stuck? I don't think so. Do I miss how we say good night to each other through the walls of our bedroom using Morse code? (taps out "no" in morse code)

Sheldon: By the way, how are you with zippers?
Penny: Why?
Sheldon: Well, I really need to go to the bathroom, and this ones gone all cattywampus.

Penny: This is ridiculous. Why am I upset just because hes off having a good time?
Sheldon: Well, perhaps you're obsessively picturing him engaged in drunken coitus with another woman. Is that it? Did I get it right?
Penny: Okay, that- that's great. You can stop trying to make me feel better now.
Sheldon: Actually, I can't. Before Leonard left, he made me promise that I'd take care of you.
Penny: He did?
Sheldon: Yes.
Penny: Oh, that's really sweet.
Sheldon: Plus, if I do a good job, he said he'd bring me back a Sailor's cap.

Penny: Okay, look, here's something people do not know about me. When I first moved out to L.A., I did a topless scene in a low-budget horror movie about a killer gorilla. Ugh, after I did it, I felt so ashamed. Thankfully, that thing never came out.
Sheldon: I've seen that. Yeah. "Serial Apeist". Howard found it online the day we met you.
Penny: Oh, God.
Sheldon: And it was literally the moment you walked out the door.

Barry Kripke: Ignore him, President Siebert. I'm sure a young man such as yourself has a perfectly healthy prostate.
Sheldon: Oh, he's just trying to butter you up. And for the record, butter is an excellent lubricant for your rectal exam.