Leonard: So, I've got a gunshot wound. That's pretty bad-ass.
Penny: No, you've got a Reebok with a gunshot wound and an ouchie on your pinky toe.

Leonard: I play Grand Theft Auto. I know about gats. *gun fires*

Leonard: What are you afraid of?
Penny: Well, what if we do go out and I do something stupid and dump you again.
Leonard: What if I dump you?
Penny: [Scoffs] Come on, be serious.

Leonard: Penny and Leonard 2.0. We can test it internally, shake out the bugs, and if we both think it is solid, we roll it out to the public.

Leonard: How does a miserable date end in sex?
Penny: I don't know, it's complicated.
Leonard: Well, I'm a pretty smart guy and right now my brain has dibs on the blood supply so give it a go.

Leonard: Some kind of nerd? I'm the king of nerds.
Penny: What does that mean?
Leonard: It means that if someone makes me mad, I won't help them set up their printer.

Sheldon: Hard as this may be to believe, it's possible that I'm not boyfriend material.
Leonard: Glad I was sitting down for that.

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" but while thinking "good, Leonard remains available."
Sheldon: You're a lucky man Leonard.
Leonard: How so?
Sheldon: You're talking to one of 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: Sheldon, you do this all the time! You fixate on some crazy idea then blow it way out of proportion.
Sheldon: Name one time I've ever done that.
Leonard: How about the time you put GPS trackers in your garbage because you thought North Korean spies were stealing your doodles? The chicken nuggets you thought were human nuggets. The mysterious cloud that was following you around town. Or the time you put my shirt on by accident and thought you were growing again.
Sheldon: I said name one. You need to work on your listening skills.

Sheldon:He'll be back.
Leonard: (Through the door) Of course, I'll be back, I live here!

Leonard: Going to Wheaton's party is not betraying you.
Sheldon: Oh, of course you would have to believe that. Evil always thinks it's doing right. Excuse me, Stormtrooper. These are the droids you're looking for.
Leonard: I'm going to a party. I'm not turning R2-D2 and C-3PO over to the empire!
Sheldon: Not yet.

Leonard: Oh. Watch out, Sheldon. This little boy Casper is a g-g-g-ghost!
Sheldon: Droll.
Howard: Not as droll as a grown man passed out in a puddle of his own urine.
Leonard: That was pretty droll. With a hint of ammonia.

Leonard: Well, they say at the end of your life, you regret the stuff you didn't do more than the stuff that you did. And, I'm pretty sure Alice is the stuff I want to do.

(Leonard & Alice are kissing)
Leonard: Damn it, I can't. I can't do this.
Alice: Is it my tongue stud? 'Cause if that freaks you out, you're in for a real surprise later on.

Leonard: Come on, she's your friend. Step up! [Knock * 3] Amy. [Knock * 3] Amy. [Knock * 3] Amy. (Turns to leave) Bye!
Sheldon: Where are you going?
Leonard: I'm single, I don't need this crap.