Raj: Hey, Leonard, will you please tell Howard my sister's never been attracted to him.
Leonard: C'mon Raj, how am I supposed to know who she's attracted to? Or was attracted to. Or who she might be attracted to. In the future.
Sheldon: And I have nothing to contribute to this conversation. Because I too know absolutely nothing about Priya's preferences in male companionship. And with that, I will re-zip my lip.