As said by J-Roc on "Trailer Park Boys", a mafucka is the urban bastardization of motherfucker (q.v.) however its use can vary widely, see example:

Intelligence agency term for "psychological operation". A government or corporate-sponsored operation, usually taking the form of a "terrorist attack" or "crazed gunman on a spree", with the intent of panicking the public into demanding more police and laws inhibiting freedom. Psyops are usually carried out by drugging a civilian or group of civilians with aggression-promoting drugs, psyching them up, arming them, and sending them out to commit mayhem. Government-sponsored terrorism. See also blackshirts, conspiracy

Derived from the rapper Jroc from the Canadian tv show Trailer park boys, just another way of sayin Mother Fucker, just with a twist

The pimp way to day motherfucker