I went on a fly-down fly back long range tuna trip on the Qualifier 105 out of San Diego to teh Revillgigedo island chain including Roca Partida, Clarion, etc.
While fishing at Clarion, the bored Mexican Navy guys came with their H&K MP5's. a boatload of them.
The captain had us prepped in advance that anyone caught giving any of them the most innocucous handout like a cigarette would be keel-hauled.
He said the reason for this is the first time they learn that a roust will result in a handout, the serious rousting will begin. Sure, the navy guys looked and looked for a half hour for irregularities, but he capitan was onto that, and had everything squared away.
I think the analogy is don't feed the bears. As to passports, if I was dealing with some thrid worl banana republic, I would have a spare passport hidden and tell them to screw themselves, but hey, you know me! lol