These days, it now is used to follow a witty response or comment to insult someone or "zing" them (See: Zing).
Other versions of "Hiyo":
"Heyo" , "Heya" , "Hiya" ,"Hoyo" etc.
It is used unecessarily and unsincerely these days due to most people's ignorance and failure to understand its history and true meaning.
man2:"Yes...it is used in the movie "Anchorman" and the song "Naive melody" in a completely different way."
man1:"exactly, these kids using it these days must be trying to impress people...although they're failing miserably."