The diploma thesis is focused on the speech of secondary school pupils. The aim of my thesis is to outline the main issue of pupils' and students' slang. The first part is theoretical and describes the differentiation of national language, formal expressions, informal expressions and informal half-formations of the national language (professional speech, argot and slang). Then the thesis analyzes the ways of creating particular slang expressions and literature that deals with this topic and defines the elder-school age period and adolescence. The second part of my thesis is focused on the speech of pupils' and students' slang. The third part is practical and reflects the expressions that were stated in the questionnaires by the pupils, eval...