I've been entertaining this idea for a while.
Train a NN/markov chain on enough of my own and publicly available facebook posts and comments that I can make it spew out realistic-looking posts and comments on demand.
Make another script that likes and unlikes pages, joins and leaves groups.
Make another that uploads random photos (or randomly generated image content) and tags me in them.
Stitch them all together into something that runs all of those on my account, generate so much noise that it becomes a tedious exercise to identify real comments and posts simply by virtue of volume.
For bonus points, run it from my home computer.
Would it be perfect? Probably not, there's probably way more you could do to simulate a real user, but it'd make a fun project if nothing else.