Somebody who is all on facebook all the time and likes and comments on everybody else's posts and photos, but refuses to do the same to yours.
Announcing some good news such as you are engaged, got married, are pregnant, bought a house or had a baby and everybody else likes except that one hater of yours, and yet they are on Facebook because they are posting, commenting and liking other non-important posts. They also refuse to like any nice photos or other great quotes you share, and refuse to give props where it is due. This is a hater in real life and Facebook life, but they make so obvious on Facebook by being the only one that refuses to like your comments, photos, good quotes and other good news shared through Facebook. "Facebook Hater"