1. an expression of approval and thanks for a good deed, OR, 2. can be used in sarcasm to show disinterest in someone's actions or feelings
1. Miss Utility: "I'm not wearing any panties."
Tito: "That's whats up good lookin out!"
Danny: "I got laid off today. I need to look for a new job."
Tito: "That's whats up good lookin out?