Referring to the condition of a person's foot. A person who does not clip their toenails, wash their feet, and lets their feet smell, all with no shame or attempt to hide it. Feet that resemble the foot of the Christmas Krampus. A creature that looks like the lovechild of Big Foot and the Devil.
Did you see the Krampus Foot on that person?
Dude! You really need to take care of that Krampus Foot.