Green’s Dictionary of Slang

(orig. US) euph. for motherfucking adj.

1958		W. Motley Let No Man Write My Epitaph 128: Them emeffing guards is bringing it in in fountain pens.
1973		A. Childress Hero 34: All over the emm-eff community [HDAS].
2000		K. Walker ‘The Kings of Comedy’ WalkerWorld 🌐 The ribaldry extended to a bawdy linguistic lesson on the permutations of the word emeff by Bernie Mac, who tells us it’s a noun. ‘The emeff owes me 35 emeffing dollars. I ain’t seen the emeff since. But next time I see the emeff, he better have my emeff money…’.
2006		posting at Worth1000 🌐 She’s part of some club that’s into bugs, on her way to some kind of rally somewhere. And that’s one big emeffing bug!