Penny: Why can't all guys be like you?
Leonard: Because if all guys were like me the human race couldn't survive.

Leonard: So if you are considering going into experimental physics, my door is always open. Once again, I'm sorry that the demonstration didn't quite work out. But now we know what happens when you accidentally spill peach snapple into a helium-neon laser. The short answer is don't.

Leonard: By the way, my leg is killing me. Thanks for asking.

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.

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.

Leonard: You come to the end of the tunnel and find a large chest. What do you do? And, Howard, do not say, I feel up the large chest.
Howard: Excuse me. I'm a married man now. I wasn't going to say anything so juvenile.
Leonard: Great. What do you do?
Howard: I walk up to the large chest, bury my face in it and go blublublublublublublublu!

Raj: Leonard, give me a beat.
Leonard: I will not.

Leonard: Oh, I forgot about this (sweater). My aunt made it for me when I finished college.
Penny: Aww, did she hate you?
Leonard: Why because I got an ugly, itchy sweater and my brother got a car? No, I was her favorite!

Leonard: Ooh, flowers and chocolates? Somebody's trying to get me out of my panties.

Penny: Aw, jewelry. Oh my God, Lakers tickets!
Leonard: It gets better. Instead of me you can take someone who will actually enjoy it.
Penny: You are the best boyfriend ever.
Leonard: Seriously, please don't make me go.

Howard: Lots of people wear matching pajamas who aren't dating.
Raj: Like who?
Howard: Like you and your dog.
Leonard: Don't rule out the dating.

Kevin Smith: I'm actually in pre-production on a movie right now. Way different than anything I've ever done before. It's called Clerks 3. You should come over and read for a part.
Penny: Oh, my, I would love that.
Leonard: You have a new job.
Penny: Well, maybe I can do both.
Leonard: I don't think you can do both.
Penny: I don't think I asked you.
Kevin Smith: Yeah, you tell him, Penny.
Leonard: Stay out of it, Kevin Smith.

Penny: Thanks for cooking.
Leonard: My pleasure.
Penny: That carrot was delicious.
Leonard: Yeah. I wish I'd fought harder for the rest of 'em.

Officiant: Is that the song from Toy Story?
Penny: He loves that movie.
Leonard: (emotional) I do.

Dave: OMG! Aren't you Leonard Hofstadter?
Leonard: Yeah.
Dave: I saw you speak at Stanford with Sheldon Cooper! Amy, can you believe it? It's Dr. Leonard Hofstadter!
Amy: No. Pinch me.
Dave: It's an absolute pleasure to meet you. Can I shake your hand?
Leonard: I don't know if you want to do that, I was just-
Okay, never mind.
Dave: Amy, I'm never washing this hand again.
Leonard: You really should.