Facebookstitute 

One who prostitutes themselves on facebook by adding strangers to increase their friend total.

I signed into facebook this morning and I had 12 friends requests from facebookstitutes. I have no idea who they are, but they must be desperate for friends.

Facebookstitute by Susie Stewardess May 14, 2009

Facebookstitute 

Someone whose gains an above-average level of pleasure from posting something on Facebook or liking every status they come across.

Ned: "Kelly's such a facebookstitute, man. I caught her liking all of my comments."
Bob: "Wow, bro."

Facebookstitute by The Bacon May 14, 2013