Everybody needs to take a breath. The door didn't close, the parking brake didn't come off, some guy threw on a jacket with epaulets and somehow snuck up into the flight deck-- maybe the flight crew was there, maybe not, at some point before things got serious they get around to asking him questions, and booya, he's off the airplane and in cuffs. Our system works, this is a good time to just remember to always check the CASS and the required paperwork-- which we do all the time anyway. Case in point, today.