Motherfucker (muhth-er-fuhk-er), sometimes abbreviated as mofo, mf, or mf'er, is an English-language vulgarism. Rather, it refers to a mean, despicable, or vicious person, or any particularly difficult or frustrating situation.
See also: Jackie-O Motherfucker, The Motherfucker with the Hat, Hello Motherfucker!, Motherfucker (disambiguation), John McClane, and Seven dirty words.