Leonard: What are you doing?
Sheldon: What does it look like? I'm playing sad harmonica in an apartment as empty as my heart.
Raj: Why?
Sheldon: I got the blues. My baby done left me.

Sheldon: Uh, I know it's not your birthday, but if you're interested-
Amy: I am.
Sheldon: Okay. Oh, and just to be clear, I'm not being intimate with you in order to keep you from going.
Amy: I wasn't thinking that.
Sheldon: Well, no, it's just, I'm just warning you, you know, if you find yourself 3,000 miles away and craving a hit of this, you know I can't Skype it to you.
Amy: That's a risk I'm willing to take.
Sheldon: All right, then.

Sheldon: That was fun. It was like Mario Kart.

Jimmy Speckerman: Wow. Look at you. Little Leonard Hofstadter. I hear you're a big-time scientist now.
Sheldon: And there's the first zinger. Ouch.

Jimmy Speckerman: From what I read, it sounded like a big deal.
Sheldon: Oh, good Lord, are we going to stand here and listen to him tear Leonard apart like this?
Raj: Hey, I won a Newcomb medal, too.
Sheldon: My point.

Sheldon: I would advise the three of you that resistance is futile. I have endless patience. I once spent two-and-a-half hours on hold with Hewlett-Packard customer service just to complain about their customer service.

Sheldon: I'm sorry, so, eventually, zombies are going to attack the rehab facility where Sandra Bullock is?
Penny: Yes, Sheldon. Keep watching.
Sheldon: You know, it's a shame, all that work she's doing to get sober, only to be torn apart and eaten alive.

Sheldon: Ill tell you where I've been. You boys may have had gelato with Stan Lee and gotten autographed comics, but I saw the inside of his house and got an autographed application for a restraining order.
Howard: Sweet.
Sheldon: Plus, I get to hang out with him again at the hearing. This is going to look great hanging next to my restraining order from Leonard Nimoy.

Sheldon: Let's play a fun guessing game to see who gets to take me. All right, this four-letter word describes either a printer's type size or a compulsion to eat dirt.
Penny: Okay, Im not driving him.
Sheldon: No, Penny, dont give up, you can get this.

Sheldon: I don't see why I'm the one being persecuted here. Dr. Hofstadter, he was bragging about his sexual desirability to anyone who would listen. You know, and Howard Wolowitz, he spent two years using university resources building a six-breasted sex robot. Oh, and at the office Christmas party, I heard Rajesh Koothrappali refer to you several times as Brown Sugar.
Ms. Davis: Hofstadter. Wolowitz. And the last one was Rajesh Koothrappali?
Sheldon: Yes. No, yeah, but in his defense, that wasn't racist. He's also brown.

Sheldon: Well, as I predicted, I am sick. My fever has been tracking up exponentially since 2am, and I am producing sputum at an alarming rate.
Leonard: No kidding?
Sheldon: No. Not only that, it has shifted from clear to milky green.
Leonard: Alright, well, get some rest and drink plenty of fluids.
Sheldon: What else would I drink? Gasses? Solids? Ionised plasma?

Penny: Sheldon, you are a grown man, haven't you ever been sick before?
Sheldon: Well, of course, but, not by myself.
Penny: Really, never?
Sheldon: Well, once. When I was fifteen, and spending the summer at the Heidelberg Institute in Germany.
Penny: Studying abroad?
Sheldon: No, visiting professor. Anyway, the local cuisine was a little more sausage-based than I'm used to, and the result was an internal blitzkrieg with my lower intestine playing the part of Czechoslovakia.

Sheldon: Why did you set it for the day before yesterday?
Leonard: Because I want to go back and keep myself from getting a time machine.
Sheldon: You can't. If you were to prevent yourself from buying it in the past, you would not have it available in the present to travel back and stop yourself from buying it, ergo you would still have it. This is a classic rookie time travel mistake.

Leonard: Uh, here's the thing. Girls like Penny never end up with guys who own time machines.
Sheldon: I disagree. Your inability to successfully woo Penny long predates your acquisition of the time machine. That failure clearly stands on its own.

Sheldon: In addition, your premise is flawed. In the original film, Rod Taylor got Yvette Mimeaux with that very time machine. In Back to the Future, Marty McFly got the opportunity to hook up with his extremely attractive young mother.
Leonard: Those are movies.
Sheldon: Well, of course they're movies. Were you expecting me to come up with an example involving a real life time machine? That's absurd.