From Wiktionary, the free dictionary
fuck if I know
- (vulgar, idiomatic) I have no idea whatsoever
2008, Edward Stapleton III, The Believers, Lulu.com, →ISBN, page 42:Hit by a mortar or an M16 round or maybe he was dead years ago...fuck if I know.
2008, Harold L. Turley, Born Dying, Simon and Schuster, →ISBN, page 182:Fuck if I know, and honestly, I don't give a shit.
2011, Peter Brown Hoffmeister, The End of Boys, Catapult, →ISBN, page 72:Fowler is lying on the floor, switching CDs. He props himself up on his elbow. He says, “You think it'd hurt us though?” I shrug. “Fuck if I know.”
2013, Lexi Ryan, Wish I May, Lexi Ryan, →ISBN, page 169:“She's married?” “She's not only married, she's leaving. Or she already left. Fuck if I know.”
