Break them. Of course not their bones..just their spirit.
If you are weak, they will roll over on you...
First off...house meeting...then spell it out.
(1) Listen to me or I will hit you.
(2) Don't listen...and I will call your father and you are OUT. Your little Korean ass will be back in Kimchiland...and your parents will lose all the money they paid to send your ungrateful little ass here...
And be sure to turn their nationalistic and xenophobic tripe back on them.
Tell them how any shitty behavior is a blight on their ancestors honor, their families honor, and their nations honor. Tell them that their personal misbehaviors are making the previous three entities look lower than horseshit. [And that they are therefore a total disgrace.
]
After that, they should be compliant little puddles that you can poor into a clear 5 gallon drum and take on field trips.
~Alex
PS. No, my advice is not nice...but you are not dealing with just anyone. There are...Koreans.
