In South African English, "howzit" is often used as a form of greeting. The term is an abbreviated form of 'how is it going?' and the appropriate response (in the black community) is 'sharp', often doubled and spoken with the r silent.

The use of the term as a greeting is almost certainly an independent development from the cricket term for an appeal

Appeal (cricket)

In the sport of cricket, an appeal is the act of a player on the fielding team asking an umpire for a decision regarding whether a batsman is out or not. According to the Laws of Cricket, an umpire may not rule a batsman out unless the fielding side appeals...

. It comes from the Afrikaans "Hoe is dit?" which is in turn an informal variant of the formal "Hoe gaan dit?" ("How are you?). An alternative etymology is that it spread from Hawaiian via the global "surfer culture".

Howzit is also used in Hawaiian Pidgin

Hawaiian Pidgin

Hawaii Pidgin English, Hawaii Creole English, HCE, or simply Pidgin, is a creole language based in part on English used by many "local" residents of Hawaii. Although English and Hawaiian are the co-official languages of the state of Hawaii, Pidgin is used by many Hawaii residents in everyday...

 and has essentially the same meaning, though its origins are uncertain.

Compare also the full list of South African slang terms.