wha had happen was

This is slang for, "The particular incident that just occured was..." This is often used to describe an unusually bizarre situation that is likely untrue.

Caden (rental car employee): "So what happened sir?"

Dontae: "The car was jacked from my crib cuh."

Caden: "How did this happen sir?"

Dontae: "Well, wha had happen was dis dude just got all swolled up and had snatched dat piece."