Someone who was way late to the party...and finally has a Facebook.
This can be demonstrated by them asking to be your friend, and upon approval they start spewing forth unwanted comments, videos, and app garbage all over your in box. Not to mention the random Facebook live messages.
"Dude, you'll never guess who I heard from last night...Seth. He was being a total Fresh-Bookie. Sending me messages, popping up with Facebook Chat and writing all over my wall...what a douche"
That one guy/girl who you barely know (maybe you had one class with them, in middle school, and you don't remember them ever saying anything to you, and you only ever heard them speak...once) you accepted a friends request from them and then they randomly comment on an update that you post on your facebook even though you never actually talk to them.
Whoah, that kid with the crutch in Physical Science Freshman year just Facebook Sniper'd me!"