A phrase used in a state of confusion. Can be used when someone says something completely ridiculous. An expression used when "what the eff??" or "what the hell?" just don't cut it.
It is also used during experiences of shock and extreme irony.
Adam: (telling the guys a story at the lunch table) We took the car doors off of my car and put them on Jeff's car, then we drove around town for 40 minutes with the heat blasting.
Vinnie: Adam, What the Mother??? it is effing June!!!! hahah