A fork of Rural Dictionary
To accept a friend request on social media websites by people who's profiles are marked private or "for friends only", with the intent of checking out their profile pics and immediately "unfriending" them based on the gut feeling you had by seeing their initial profile pic. This also can come about via friend requests from long lost friends or exes. The underlying motive is that these people who get "Pre-unfriended" won't notice that their friend request is missing and not rejected.
Lisa, "Diane, check out your ex-high school boyfriend trying to friend me." Diane, "Eek! That's Eric, totally gave me the creeps on prom night. Pre-unfriend him and move along!" Tony, "Man, this chick can't take a hint Scottie! I have Pre-unfriended her 7 times and she's friend requesting me again!"