When one deletes a friend from Facebook because he or she knows that the Facebook friend in question would eventually delete them instead. Preemptive unfriending thus robs the deleted Facebook friend of the joy of being able to delete them.
John: Why'd you delete Bec from you friend list?
Adam: I knew she'd eventually delete me so I wanted to take the satisfaction of unfriending for myself.
John: Ah, a preemptive unfriending.
When someone you're friends with on a social network takes too much of an interest in their profile (generates an excessive amount of posts) or in your profile (generates an excessive amount of comments on your profile), and you contemplate terminating the "friend" status.
Contemplation can also be due to terminated relationships, etc.
Girl 1: Oh my God... Becky is so annoying on Facebook. She comments on like, ALL of my pictures.
Girl 2: I know, right! Right now she's Pending Unfriending.
when you're holding up your phone and making faces at it, as though you are taking a selfie, but you're really taking a picture of the person across from you or the wall or anything else that seems interesting but you don't want to be caught dead taking a picture of.
This action is often made more convincing by wiggling the eyebrows or opening the mouth, to pretend you're trying to get a Snapchat filter to work.
FRIEND A: "Did you just take a stealthie of me?"
FRIEND B (turning phone around): "no I was just using snapchat's new filter, see?"