Someone that shoves all their fingers into a females vagina, so that their knuckles are touching the taint...
by The Judge of the Northeast April 26, 2015
Tainted knuckles occur when you reach between your legs to wipe your ass after a shit and your knuckles touch the vile soup in the toilet bowl or,heaven forbid,the turd itself.
by wolfbait51 May 29, 2011