Penny: You know, we could've come to you guys. You didn't have to bring the baby here.
Bernadette: Oh, it's okay. It's good to get out of the house.
Howard: And the car ride puts her to sleep.
Leonard: Aw, that used to work with Sheldon.
Penny: Yeah, until someone left him in the drugstore parking lot and he freaked out.
Leonard: Who forgot to crack the window?

Leonard: Penny, as a scientist, my job is to figure out why things happen. But I don't think I'll ever understand how someone like me could get to be with someone like you. You know maybe I don't need to understand it, I just need to be grateful. I love you, Penny.

Leonard: What would you be if you were attached to another object by an inclined plane, wrapped helically around an axis?
Sheldon: Screwed?
Leonard: There you go.

Leonard: My point is, while you're spending all this time on your own, building computers or practicing your cello, what you're really doing is becoming interesting. When people finally do notice you, they're gonna find someone a lot cooler than they thought. And for those of you that were popular in high school, it's over, sorry. Thank you. Congratulations.

Amy: What is this?
Sheldon: I'm mapping basic topics of conversation and with whom they can be discussed.
I call these circles "Zones of Privacy". Don't Google that unless you want to see pictures of people's genitals.

Bert: I met her on G-Harmony. That's a Web site for geologists to find love.
Amy: That's a real thing?
Bert: Yeah. Their slogan is "We're all about dating and not the carbon-14 kind".

Sheldon: Two years ago I got my driver's license.
Amy: What? Why didn't you say anything?!
Sheldon: I like being chauffeured around. It makes me feel important.
Amy: So when I got up at 4:00 AM to drive you across the desert to an antique train museum, I didn't have to?
Sheldon: No, you didn't. But keep in mind, I felt extremely important.