Piercings in ones face. Usually chunks of metal sticking out of unexpected locations.
She didn't make it through security because all her face stabbings
kept setting off the metal detector.
The art of applying a slam, inflicting an insult or gossipping on Facebook. The comment is done in such a way that the reader may not even know they, or someone they know, is being Facestabbed. If the reader is fortunate, a post from someone else will connect the dots and the reader will have an "I get it moment" and know that so and so has just been Facestabbed.
I didn't even realize that Laura was facestabbing Angie on Facebook the other day.