When you have a facebook account and someone, usually a signifcant other, or someone that wants to be held in a higher postion in your pecking order feels the need to post, like, or make comments on your facebook page constantly in order to "mark their territory".
Akin to a dog "marking his/her territory" like a fire hydrant with urine.
Dennis: "I hung out with Shannon the other weekend and we had a good time."
Dennis: "But, she's left several comments and posts on my facebook page since then, it's kind of annoying."
Jeremy: "Archetypal facebook fire hydrant my friend..."
This is a person who works for the Fire Department and at every opportunity this person is posting on Facebook about everything they have ever done while on duty. This is because they are not very good at the job, so they need all of the "pats on the back" from their other fake "friends" on Facebook.
a person who is addicted to facebook. they check their facebook as often as they check their email. they are on facebook often over large intervals of time, especially when they should be doing more important things.
Man, I'm really behind in all of my classes because I've been on facebook, I tried to stop but I have to see who's poked me.
You can't really tell your friends who they can and can't be friends with, and so you eventually are force to use "block person" so you don't have to read all their stupid, annoying comments anymore.
Bob: Yum.
Kim: Cool!
Bob: Yeah, real "cool". She's making pork chops. That's a big, huge deal.
Kim: Oh shut up. I honestly have no idea why Jane keeps you around as a friend in real life, or here. You're nothing but FacebooFINE to me.
Kim: Stop it. Both of you. You're both my friends.
* Kim uses "block person" on Bob, who is noting more than FacebookFINE.