The definition to call your mother to get her angry and stare at you confusedly. It is also a great alternative to 'bro' or 'dude'. Incredibly versatile.
Moombahcore is basically Moombahton on steriods, mixing Moombahton with the harshness and filth of Dubstep/Brostep. The genre has been mainly underground throughout its existence and has only recently gained mainstream exposure.