I’ve heard the term Ex-Marine used only for one individual, Lee Harvey Oswald. (Although, I’ve also heard folks threatening to add John Murtha’s name to that list.) I suppose you can add this genius too:
In December, a former U.S. Marine from North Miami was sentenced to nearly five years in prison for stealing the identities of more than 40 fellow Marines stationed at Camp Leatherneck in Afghanistan as part of a plot to claim $54,000 in fraudulent income-tax refunds.
Your buddies are deployed and you loot their income-tax refunds. An Ex-Marine.