Leonard: Sheldon, I've known you a long time. I'm going to tell you this with all the love I can possibly muster. Amy's right, you're wrong.
Sheldon: But you don't even know -
Leonard: It doesn't matter.
Sheldon: But in my defence -
Leonard: Doesn't matter!

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: *knocks three times* Amy, Bernadette, Penny. *repeats three times*
Bernadette: He's never going to stop doing that, is he?
Amy: I don't mind. I'm hoping to put his love of repetition to good use someday.

Howard: My arm is feeling numb. *Howard rubs his right arm*
Bernadette: That's the wrong arm for a heart-attack, doofus.
*Howard switches to his left arm*

Amy: It's actually steamier than it looks. Sheldon's looking up the phallic symbolism of root vegetables in renaissance paintings.
Sheldon: Oh no, I got bored of that. I'm just browsing cuticle scissors on Amazon.