Defacebooking is sabotage of a friend’s Facebook ‘Wall’. Typical examples of defacebooking include outing the friend as a pedophile, a truant, a stealer of office supplies, a backstabber of BFFs, or a closet Mormon.
I had to un-friend Jeremy for defacebooking me! He ratted me out on my Wall for trying to poach Chase’s not quite-eighteen year old sister at Chase's party. Jeremy waited til I had just started my shift, and when I logged back on my Wall was like totally covered in flames.