To use the knuckles of the hands of your partner as a kind of stimulant for the male genitalia. proper procedure would be to cross your wrists so that the back of your hands are facing one another and to rub your hands back and forth as if to be rolling pizza dough.
n. knucklebabies is the outcome a male gets after he roughs up his suspect (masterbates) and dosent release his sperm into a sock or something and it is all over the back of his hand.
I got home late lastnight and my wife was asleep,so i went to the computer and racked out a batch of knucklebabies.