Humiliate people who smear shit on bathroom walls
I've been to some public bathrooms where I caught sight of poop smeared on the bathroom walls.
Now, I don't know why someone in their right mind would stick their fingers in their butthole to pick enough poopoo to make a noticeable mark on the wall.. But I would surely make such a person lick their shit off the wall if I caught them in this repulsive act.