Bravado aside, I would prefer to have them understand exactly what I want them to do.
I seem to recall a Japanese student type that did not survive a Trick or Treating expedition because he did not understand the meaning of 'FREEZE!'
I'd hate to stand in front of Saint Peter explaining why I shot Jose, when all he wanted was for me to call an ambulance for his brother that had encountered a rattlesnake. I live ~30 miles north of the border and I have had many more rattlesnakes in my yard than illegal aliens.