Penny: So, who is she?
Leonard: Oh, she's a doctor.
Penny: Oh, nice. A doctor doctor, or a you kind of doctor?
Leonard: Doctor doctor. Surgical resident. Smart, pretty. Let me ask you something. If your friend thinks he's dating someone, but he's not because, in fact, you're dating her, does that make you a bad person?
Penny: Well, that depends.
Leonard: On what?
Penny: Is that friend Wolowitz?
Penny: Screw him. You're fine.