Penny: Look, sweetie, relationships aren't about money, okay? It's about respect and having things in common and- Yes, Sheldon?
Sheldon: You and Leonard don't have anything in common. Maybe you should break up.
Leonard: (To Penny) You called on him.

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

Raj: Sheldon, what did Amy have that attracted you?
Sheldon: Oh, so many things. Her mind, her kindness, and especially her body.
Raj: Really?
Amy: Relax. We're the same blood type. He knew he could harvest an organ.

Sheldon: Who's ready to laugh? [Leonard groans] Okay. So Feynman, Einstein and Schrodinger walk into a bar. Feynman says, "It appears we're inside a joke." Einstein replies, "But only to an observer who saw us walk in simultaneously." To which Schrodinger says, "If someone's looking in the window, I'm leaving."
Leonard: [chuckles] That's actually funny.
Raj: You should send that to Jimmy Fallon.

Sheldon: Hello, I'm Dr. Sheldon Cooper.
Amy: And I'm Dr. Amy Farrah Fowler.
Sheldon: And welcome to a special retrospective, where we will take a look back at the history of Fun with Flags on an episode we're calling,
Both: "Fun with Flags - Behind the Flags: A Retrospective."