(one word) a greeting; to ask how one is doing, has been doing or plans to be doing.
Damn!! Shorty, I ain't seen you in a minute. Whatitdo, baby?
to question the goings on in the mind of a person that is in an act of sheer ignorance.
to greet a person informally, usually a friend or person of close relation.
Guy 1: The back of yo head look ridiculous!
Guy 2: WHATITDO?!
Ay WHATITDO?! its been a while my boy.