Sheldon: Remember how Leonard told you we couldn't come to your performance because we were attending a symposium on molecular positronium?
Penny: I remember symposium.
Sheldon: Yes, well, he lied.
Penny: Wait, what?
Sheldon: He lied, and I'm feeling very uncomfortable about it.
Penny: Well imagine how I'm feeling.
Sheldon: Hungry? Tired? I'm sorry this really isn't my strong suit.