Leonard: I mean, I'm glad they're getting along, but it's starting to make me uncomfortable.
Bernadette: Well, are you worried he's like another man in her life?
Leonard: A little, until I saw them in matching tops.

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: Wait, are you saying if we combine my experiment with your calculations, we can determine the precise moment in time when the wave function collapses?
Sheldon: It could be the most inspired combination since I mixed red Icee into my blue Icee. It was like drinking 2/7ths of the rainbow.
Amy: Sheldon, this is really interesting.
Sheldon: Yeah and this one won't stain my teeth purple.

Amy: Why don't you ask me what I'm working on?
Sheldon: Oh, very well. What have you been working on? And feel free to honk during the boring parts.

Leonard: Oh, it's just nice to be with people who are happy to have me around. Isn't that right, Halley?
*Halley starts crying*
Howard: Well, at least someone had the courage to say it.