Vulgar slang, Caribbean Patua. Contraction of "mother's" & "cunt" implying that the person is stupid or ignorant, as though they had just come from the womb. Akin to "wet behind the ears." Also used in general as an insult or in reference to somebody, as one would use "motherfucker" in the states.
Boys who enjoy yaoi (a genre in Japan that contains sexual and/or romantic relations between two men); literally translates to "rotten boy"; corresponding female : fujoshi