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:
Synonyms for mafucka
On this page, you will find 30 slang terms related to mafucka. Some of the top words include: muhfuh, mu'fucka, muzrucker, Muthafucka, Fack, and 25 more.