The life cycle of urban slang:
Stage 1: The miracle of birth. Somewhere in the United States, young African Americans decide to start using “holla” (as in “holler”) to describe talking to each other. “If you need anything, holla at me.”
Stage 2: The use of “holla” spreads and evolves. At some point, a rapper decides to yell it to a crowd, a call for a response. “HOLLA!” It becomes a trademark catchphrase for the Rocafella label. Other rappers like it, want to get in on the action.
Stage 3: Holla becames available for home use. People full of hot air who are in jobs where it’s important to maintain an image of with-it-ness (mostly commercial radio DJs and BET hosts) overuse the term.
Stage 4: White people find out and start using it. They sort of have a sense of what it might mean, but it doesn’t matter because it’s divorced of all context. It’s supposed to automatically denote insider status or “being down.” The meaning of the word “Holla!” is now “I have heard this word, ‘Holla!’ and I can prove it by saying it out loud!”
Final stage: A cartoon animal or elderly person says it in a movie, and that’s supposed to be funny.