Amy: I just read about an experiment designed to see if you can make two people fall in love in a matter of hours.
Leonard: That doesn't sound right. My research has shown it takes three to five years of shameless begging.
Penny: Honey, neither of us comes off good in that story.

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.

Sheldon: This song is never going to stop. Have you ever dealt with something so relentlessly irritating?
Leonard: That's a trick question, right?

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.

Howard: I'm sorry I didn't take you to the airport. I just want you to know I'll never forgive myself for being so selfish. And I promise to keep you close for the rest of my life.
Bernadette: Oh, no, that thing's gonna end up in my bedroom.

Bernadette: You better find my husband's mother, 'cause one way or another we're walking out of this airport with a dead woman.

Penny: Do you want to stop? I know you have trouble with eye contact.
Sheldon: Well, you have a brown fleck in your right iris that looks like a Formula 1 race car, so I'm just concentrating on that. Plus it's easier around people I'm comfortable with.
Penny: Oh, sweetie, I'm comfortable around you, too.
Sheldon: Of course you are. I'm warm and soothing. I'm like a human bowl of tomato soup.