Any military types know what whould have happened to to less high-profile marines involved in something like this at other foreign postings - say in Germany or Iraq?
Are you subject to local jurisdiction as well as the UCMJ?
Marine Security Guards usually carry Diplomatic Passports. If the embassy believes that they were guilty, they’d be flown out the next morning to the Security Guard Battalion HQS at Quantico. I don’t think non-judicial punishment would be meted out; rather, I believe, they’d be reduced in grade and either discharged with prejudice or if it were serious enough, they could end up on the rock hockey team. I’m sure that the leadership of the battalion would not be amused by the Marines’ misconduct, and bringing their outstanding record into disrepute.
Only if the locals catch you.