A chronic, habitual masturbator. Someone who is always giving himself a tug. Typically addicted to
porn, stalks
Facebook, Insta and other media for pics to fap off to.
May also be used as a derogatory term for somone who’s a POS.
My neighbor is a real jack knuckles. He’
s always giving himself a wank online.
My uncle is a jack knuckles. I catch him tossing off every
time I walk past the den.
Fuck that
guy. He’s a jack knuckles.