Leonard: [to a "smiling" Sheldon] We're here to see Koothrappali, not kill Batman.

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.

Leonard: Oh, hi, you wanted to see me?
Ms. Davis: Yes. I wanted to talk to you about the e-mail you sent me last night.
Leonard: I sent you an e-mail?
Ms. Davis: You bet you did. "Hello. Shalom and aloha from the grave of Richard Feynman."
Leonard: (groans) Oh, it's coming back to me.
Ms. Davis: "Please accept the following retraction: I know I said physics is dead, but it is the opposite of dead. If anything, it is undead, like a zombie. Speaking of which, if Richard Feynman came back as a zombie, I would totally let him bite me."
Leonard: Any chance that's the end?
Ms. Davis: "I got bit by a squirrel once. I had to get rabies shots. I cried so much, my mother said 'don't be a baby'. In conclusion, physics is great. Squirrels suck, and someday, I'm gonna put my mom in a cheap nursing home. Yours truly, XOXO, Dr. Leonard Hofstadter."
Leonard: I-I-I can explain.
Ms. Davis: "P.S Can you come pick us up? The Uber driver won't open the door because Sheldon is covered in blue vomit."

Howard: Sheldon, don't take this the wrong way, but, you're insane.
Leonard: That may well be, but the fact is it wouldn't kill us to meet some new people.
Sheldon: For the record, it could kill us to meet new people. They could be murderers or the carriers of unusual pathogens. And I'm not insane, my mother had me tested.

(Sheldon smiles in a grotesque way).
Howard: Oh crap that's terrifying.

Sheldon: I often forget other people have limitations. It's so sad.
Howard: He can feel sadness?
Leonard: Not really. It's what you and I would call condescension.