Penny: You asked Stephen Hawking and not her father?
Sheldon Cooper: Stephen Hawking's a genius. If he said no, I wasn't gonna waste my time on her father.
Amy Farrah Fowler: But you did ask my father?
Sheldon Cooper: I did. He said yes. Although not in a robot voice, so it wasn't nearly as cool.
Penny: Okay. Oh, my god, I can't believe you guys are engaged.
Sheldon Cooper: We're not engaged yet. She's taking forever to answer.
Amy Farrah Fowler: Because you're on the phone!
Sheldon Cooper: We'll call you back.
Sheldon Cooper: She said yes.