Local elementary school in my town had to do just that. The hispanic kids -were- using Spanish to insult and bully other kids, around adults that didn't speak it. When they got teachers in who did understand it and cought them, their parents threw a fit that their darlings would never do such a thing. No one ever complained before! Sued the school and lost over it, because the nuns banned Spanish outside of Spanish class in the building. I know just enough spanish to get me in trouble (mostly just the insults and the numbers) and have seen that happen around our school. The kids smile oh so sweetly, while calling another teen girl puta and such.