Leonard: Ladies do love a guy dressed like a kitchen garbage bag.

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.

Raj: Amy, good luck getting these guys excited about a dinner with a theme. I gave up when no one cared about my Tom Hanks-Giving.

Sheldon: Let's see. What do I know about Amy? She loves medieval literature. Chaucer's her favorite. And her eyes sparkle when she watches old French movies. And I enjoy how harp music causes her fingers to dance as if she's playing along.
Bernadette: Wow, you really do love her.
Sheldon: I do. Now, let's find the kind of gift that makes her feel small and worthless.

Santa: All right, let me see if I've got this straight. A picture of you on my lap is a way to punish your girlfriend for making you celebrate Christmas?
Sheldon: Correct.
Santa: Santa thinks dating you might be punishment enough.
Sheldon: There's an argument for that, but I want to make sure.