Currently, there exists an alarming phenomenon among the youth that they create their own language, especially teenagers use slang, complex symbols, rhythmic sentencescalled "teens" proverbs-idioms, Vietnamese mixed with foreign languages, and several words written in spoken language but in an extremely ungrammatical way. These phenomena have broken the general rules of Vietnamese written language. What should the authorities do to preserve the purity of the national language? It is time to have a reasonable language policy, to have a more consistent policy and to have a close coordination between the family, school and society in order to keep the purity and essence of Vietnamese. This relation has become basic principles of Vietnamese education.