A play on words. Originally "or what" is an addition to a question requiring a more definite response for example, "Let's go eat, or what?". Yet now we ask simply "what" and then add "or what". Usually it is used to ask the simple question "what" however this new addition, "or what", creates a weird order of words eventually provoking the responder to become confused.
Jorge: Hey man let's go pound, or what?
Andres: Yea bro i am so down to do that right now.
Jorge: Are you paying?
Andres: What or what?
Jorge: Uh, what?
Andres:What or what?