An expression of hatred or a way to get revenge.
The protagonist defecates onto a piece of plastic wrap, wraps it, and places it in the freezer. Once it is fully frozen, he/she takes it, along with a sturdy cheese grater, to the (temporarily vacated) home, car or office of the enemy, and proceeds to grate the frozen shit all throughout the interior.
It is most effective when the gratings are deposited into all nooks and crannies, down the back of couches, inside drawers, etc etc.
A nice finishing touch is to then leave the heating on.
That fucktard never paid me back my $10, so last night, I poo grated his entire house.