How to overcome naughty students?

Indonesia
August 21, 2008 11:57am CST
I am an English teacher of a vocational school (here in Indonesia called as SMK = Sekolah Menengah Kejuruan). Most of them are boys, and sometimes they are very naughty. I feel confuse how to overcome their naughtiness. It is hard for me to teach English to them since English is our foreign language. I often tell them that when we are learning a foreign language, please don't use our own "kingdom" language - I mean our mother tongue language, since as I have experienced when I was in university, I used to use my mother tongue language - Javanese - then I felt hard to learn English. I used Indonesian language at least when we discuss to friends. And then, the next I used English as daily means of communication. What do you think of overcoming the students' naughtiness, everyone?