Mocking Facebook Users' posts that are intended to be serious. Usually applied to users who continuously post self-absorbed messages or seek attention or pity.
FB User: Ugh. I'm getting a migraine again.
Facemocking reply: Maybe you should pull yourself away from your computer for 5 minutes.
Jon is drunk out of his mind and is lying on the floor with his tie wrapped around his head. Matt flips out a camera and says: "Hey, this is a great picture to put on Fecebook."
A "playful" offensive term similar to "Jerkface". Often used against someone in a derogatory manner. This word can be easily adapted to an individual's arsenal of "FACE" insults.
Person 1: "These cats are bothering me!"
Person 2: "Your FACE isbothering me!"
Person 1: "Damn it Person 1 you're such a FACEMONGER"