The youth slang in the Bulgarian language origins in the beginning of the 20th century. Currenyly it is a system with specific language properties and represents a subsystem of the standard language. The dictionary of slang contains mostly the nouns, the adjectives and the verbs. The sources of the noun formation are: old social dialects, standard Bulgarian language, foreign languages, the movies, the modern music and the television. The most important modes of formation of the nouns are: semantic derivation (methaphoric transformation of the standard semantics), lexical derivation (use of expressive word with standard suffixes), formal modification of the foreign nouns, mainly from English. The standard Bulgarian words are semanticly changed, while the foreign words are adapted to the Bulgarian language system.