Cryptic posts in facebook that express a vague sentiment but do not provide any details, clearly designed to bait friends to ask follow-upquestions.
A facebook wall post that could be considered facebait would be posts like "Today is the day!" or "Ugh, I am over it..." or "Now I know why I should stay home..." or "Hurt and disappointed..."
When two or more people have a mindless heated argument on Facebook, whether it's through comments on profile pictures, profile walls, etc.
Person #1: You hear about the fight after school today?
Person #2: No, what happened?
Person #1: Did you see the facebeef on Samantha's profile picture? The one with her and her boyfriend John.
Person #2: Hahaha, oh yeah. Sam's ex left a comment asking if he was enjoying his sloppy seconds. Then John commented back and said he was gonna kick his ass.