Sheldon: If any of you are looking for something to do on Valentine's Day, Amy and I'll be streaming our first-ever live episode of Fun With Flags. You're welcome to join us as we celebrate the timeless love affair between wind and flapping fabric.
Leonard: Penny and I have dinner reservations that night, but any other time, no.

Raj: I'd like to propose a toast to our friend, Howard. His, um, his big heart, his beautiful soul-
Leonard: And his tight little pants that somehow did not make him sterile.

Amy: So Sheldon, there's something I've been wanting to talk about but I know it's kind of a touchy subject.
Leonard: Way to narrow it down to everything.

Penny: Wait a minute. You mention his birthday and he vanishes?
Leonard: Well, where's that information been this whole time?

Raj: Hey, so what was Adam West like on the phone?
Leonard: Uh, nice guy. But it was a little weird to hear Batman say, "Don't ring the doorbell or my poodles will go crazy."

Howard: See, he's not wearing a tie.
Leonard: Well, he's a patent attorney. Maybe his tie is pending.

Leonard: Hold on, hold on. So the three of us do all the work and only end up with 25%? Patent Attorney: Dr. Hofstadter, this university has been paying your salaries for over ten years. Did you think we do that out of the goodness of our hearts?
Leonard: Well, until you just said that mean thing, kinda.

Leonard: Guys, everyone is involved in this, okay? Howard's invention, Sheldon's math, my original theory that space-time was like a supercooled liquid. Which I'm sure Penny would've mentioned if she wasn't working on that hangnail right now.
Penny: What?

Leonard: This is cool. When was the last time you and I built something together?
Howard: Scientifically? A little over a year ago. LEGOs? Last week in my room.
Leonard: If there was a Nobel Prize for Millennium Falcons that fall apart when you pick them up, we'd be set.

Penny: Sheldon, what did you do?
Sheldon: Well, I'm not proud of it, but I jaywalked.
Leonard: Oh, no, it's like a horror movie. We're trapped in a cabin with a maniac!

Leonard: Really? The guy who for years couldn't even talk to women is suddenly going out with two of them? How is that possible?
Howard: I know. Scientists have tried to reproduce it with computational models, but, in each case, the world blows up.
Leonard: Seriously, that guy's dating two women?

Penny: What about your weird relationship with him?
Leonard: That's different. I'm like the little girl in Poltergeist and he's the creepy thing in the TV.

Penny: All right, well, let me know if you guys want to go.
Raj: I would love to. I do enjoy the complexity of an aged Pinot noir.
Leonard: I'm sure that would pair nicely with your fried nuggets of chicken.

Leonard: The difference is she's bringing life into the world, and you suck it out.

Penny: You really want me to pick up your mother all by myself?
Leonard: Hmm, I just feel like it would be a good chance for you to bond.
Penny: Or a way for you to avoid her?
Leonard: I don't know what he's putting on those cards, but you are smarter than ever.