When a facebook friend of yours cleans out their friendlist and you realize that you have unwittingly survived a, on their part, mass friend deletion of epic proportion.
"Your friends list when from like, 650 down to 225. Guess I survived the defriendocalypse, eh?"
Basically a friend that is scary to others outside of the friend group, the person is usually alt and they have the same effect on strangers as walking with a Rottweiler
Alex is my scary dog friend, when I want to walk alone at night I call them
A.J. Scares off creeps, he's totally a scary dog friend
public defriender (noun): an individual who frequently and/or openly discusses removing people from their friends list in a self-righteous and attention-seeking manner.
"deleting some ppl from my fb who longer serve dey purpose. #realtalk"