Used to ask one which gang and/or group the associate with. Much more "gangsta" then "Who are your friends?" Used at the beginning of every episode of The Bernie Mac Show and in one episode can be seen embroidered on the back of Bernie's maroon, velvet outfit.
Bernie (to crowd): Who you wit?
Crowd (to Bernie, all together): Who you wit?
This dialogue continues until Bernie actually starts his act, however unfortunatelly for both parties neither found out who the other was "wit" and the question "Who you wit?" goes unanswered for all of eternity.
White translation: Who are you trying to mess with?
"Finna" directly means "fixing," a common southern-slang word that is used in the place of "going to do" or "attempting" and "try" is used in the place of "challenging." Combined, finna try means "fixing to do" which is then used to say, "who are you fixing to mess with" or "who are you trying to challenge."
It is a horribly structured phrase that is used when someone is acting extra tough or sassy and is challenging the one they are speaking to. It contains words that are not even real in the english language and should only be used if you are feeling in an extremely ghetto and uneducated mood
Person A gets all up in the grill of person B
Person B: "Who you finna try? Who you finna try? I bet it ain't me, I bet it ain't me, AHHHHHH"