I just re-read this sentence from that Wikipedia page for "Yo! MTV Raps!" whose link I provided above:

"Yo! MTV Raps is a two-hour American television music video program, which ran from August 1988 to August 1995 through its identity of Yo! MTV Raps (and until 1999 by the name Yo!)."
-snip-

Is that "1999" in that sentence a typo for "1989"? If not, I'm not sure how the show could have been known as "Yo!" in 1999 when it went off the air in 1995.

Yo! Someone else makes typos besides me. :o)

**

I should have been clearer that one of the ways that the English word "Yo" is used is the same as the English word "Hey!".

See these definitions from http://www.urbandictionary.com/define.php?term=yo:

yo
   
1) A contraction of the possessive prenominal adjective "your."
2) An informal address or title to one whose name is not known to another; can be used as an interrogative address.
3)A declaritive or imperative exclaimation, whether alone or within a sentence.
1) How's yo momma?
2) Hey, yo! What's up, yo?
3) Yo! What the hell do you think you are doing?! Yo, just do your job! YO!
by Dr. Thompson May 12, 2003