Learn English – the correct term for unboarding passengers from aircraft

Unauthorized engagement (of the enemy) is the term I would use.

Fighting the enemy in military terms is frequently referred to as engaging the enemy. Without permission, it would be an unauthorized action.

Vigilantism could be applied to this sort of action, too. But, I agree that usually comes with a sense of justice attached to it.

Alright, I figured it out by searching for "believable facetious argument." I was a little bit off on my definition of it, and it's more of an internet adage than a part of actual English usage. Poe's law is what I was thinking of.

From Wikipedia:

Poe's law is an Internet adage which states that, without a clear indicator of the author's intent, parodies of extreme views will, to some readers, be indistinguishable from sincere expressions of the parodied views.

Thanks for the help though, and upvotes for the effort. :)