Green’s Dictionary of Slang

a synon. for motherfucker n.

1969		B. Beckham My Main Mother 147: Where you muh fuhs from? [Ibid.] 148: We’re badder than all of those jivetime, pussy muh fuhs.
1972		T. Weesner Car Thief (1973) 104: Watchouttamawaymuhfuck — stompmuhfuckinassman!
1974		Village Voice (N.Y.) 11 July 23: I had a .22 in my bag because I was headed for the New Lots and them muh-fuhs are superbad.
1981		H. Gould Fort Apache, The Bronx 87: Hey muh fuh, I ain’t no junkie.
2001		S. King Dreamcatcher 460: That’s mine, muhfuh.