There are some sound effect words, or onomatopoeias that just can't be used after something. Writers Bendis and Mack and/or letterer Joe Caramagna should know that (I'm sure someone as foulmouthed and internet-savvy as Bendis knows it) "fap" is used as a verb on the internet to refer to male masturbation. It's not a secret, and it's actually derived from the sound of the hand slapping the thigh, so it IS an SFX...
I have seen it before in a couple of books; but only once or twice... this double page spread is just... too much.
The hotel room exterior, the Jack and Matt Murdock murdock clippings, the nun picture (yeah, I know it's Matt's mom)... all that makes it even more disturbing. The last panel provides a clue, and the next page shows us it's just someone punching a sandbag:
Can we not use that SFX except for what it's intended?
(From Daredevil: End Of Days #8 of 8, by writers Brian Michael Bendis & David Mack, and/or letterer Joe Caramagna.)