Sheldon: Carbon. Hydrogen. Carbon. Carbon. And last but not least, carbon.
Leonard: This might be the glue talking, but that was a very pleasurable 139 and a half hours.
Sheldon: Agreed.

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.

Sheldon: Thank you, Dr. Fowler. I have a very long and somewhat self-centered speech here. But I'd like to set it aside.
Penny: Yeah!
Howard: Way to go!
Sheldon: Because this honor doesn't just belong to me. I wouldn't be up here if it weren't for some very important people in my life. Beginning with my mother, father, meemaw, brother and sister. And my other family, who I'm so happy to have here with us. Is that Buffy the Vampire Slayer? I was under a misapprehension that my accomplishments were mine alone. Nothing could be further from the truth. I have been encouraged, sustained, inspired and tolerated not only by my wife, but by the greatest group of friends anyone ever had. I'd like to ask them to stand. Dr. Rajesh Koothrappali. Dr. Bernadette Rostenkowski-Wolowitz. Astronaut Howard Wolowitz. And my two dearest friends in the world, Penny Hofstadter and Dr. Leonard Hofstadter. I was there the moment Leonard and Penny met. He said to me that their babies would be smart and beautiful. And now that they're expecting, I have no doubt that that will be the case.
Penny: Thanks, Sheldon. I-I haven't told my parents yet, but thanks.
Sheldon: Oh. I'm sorry. Don't tell anyone that last thing. That's a secret.
Howard, Bernadette, Raj, Penny, Leonard, I apologize if I haven't been the friend you deserve. But I want you to know in my way, I love you all. And I love you. Thank you.

Howard: How you doing?
Bernadette: Fine. Why?
Howard: Well, this is the furthest we've ever been away from the kids. I was just checking to see if you're okay.
Bernadette: I'm on my second Jack Reacher. I'm doing great.

Bernadette: You realize it's been years since we've got away just the two of us.
Howard: I know. I can't wait. Fancy hotel room. The big bed.
Bernadette: Yeah. We're gonna sleep our asses off.