The paw marks that your beloved feline pet leaves after she has had a dump in the litter box and trod in her somewhat damp turd. When she exits the box to come and say hello and be told what a good girl she is there is a shitty trail of paw prints on your floor

When you eat dirt for the first time and leave your family to build a shack in the woods

The muddy foot prints left on toilet seats by whatever nasty bastard still hasn’t learned how to navigate a modern bathroom.

The act of touching something after your fingers have touched your butt hole.