The article studies the abbreviation ‘HZ’ (‘nobody knows’). The aim of this research is to find out in what meaning ‘HZ’ is used and how this abbreviation functions in everyday oral speech. The paper presents the results of lexicographical analysis of authoritative dictionaries, data obtained from the survey among linguists (students and professors) as well as data from the social network twitter.com. The lexicographic and contextual analysis revealed that HZ is not only an abbreviation, with the included swear word, but it also used to express one’s own or someone else’s lack of knowledge. The linguistic survey showed us that the investigated item is best known to young people who communicate more on the Internet. In addition, we have analyzed 500 uses of the word HZ in the social network twitter.com. As a result, we managed to find 142 contexts which included pejorative, in other cases, HZ expressed, rather, lack of knowledge of a speaker or writer and was similar in meaning to adjectives such as unknown or unclear. Furthermore, it was found that HZ tends to lose its lexical meaning completely and get pragmatic meaning in oral discourse, that is, to undergo a process of pragmaticalization.