What up YouTube is a familiar opener from online video culture, where creators greet their audience directly before getting into a vlog, challenge or commentary. The doubled greeting gives it a meme-like rhythm that makes it easy to reuse as a short intro, reaction or parody, especially in edits that imitate a typical YouTuber opening. Because the line is instantly recognisable to regular viewers, it works as shorthand for starting a video, and short soundboard versions keep circulating for intros, jokes and creator-style sketches.