Busta Rhymes has had many collaborations with The Neptunes or should I say songs produced by The Neptunes and "What It Is" is perhaps one of the more popular ones.
I'm scratching my head right now as I try and remember what album this is from. I think it was from a Violator(management team) compilation. This is definitely a throwback because Kelis was obviously still associated with The Neptunes. It's been eight years since Kelis last worked with The Neptunes. Funny how time flies!