Raj: You guys do anything fun after dinner?
Leonard: Well, actually Amy came back over and we hung out. Did you know that we're both spelling bee champs? We stayed up for hours trying to stump each other.
Raj: Who won?
Leonard: Oh, she thought she had me with "appoggiatura" but I shut that down expeditiously. E-X-P-E-D-I-T-I-O-U-S-L-Y. Expeditiously.

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.

Howard: (singing) Alone in my temple in the middle of Peru, A giant stone ball with nothing to do,
Raj: But if you steal my idol, I will roll right over you
All: Cause I'm six tons of granite, And micaceous schist. Yeah, I'm six tons of granite, And micaceous schist,
Bert: I'm gonna crush you, I'm gonna mush you, You took my idol, I'm homicidal, Gonna roll over you till your brains come out, And your bones will crunch and your blood will spout! I'm not just a rock, baby. I'm a boulder.
All: Cause I'm six tons of granite, And micaceous schist. Yeah, I'm six tons of granite, And micaceous schist, Yeah, I'm six tons of granite-

Howard: What up, my Hebrews and She-brews?!

Leonard: Thought you were getting us dinner.
Penny: Sorry. I had to stop at Sheldon's and help him solve string theory.
Amy: What?
Penny: Yeah, turns out the answer's knots.
Leonard: That's cute, but you can't have knots in more than four dimensions.
Penny: Mmm ... you can if you consider them sheets. [chuckling] Good night.