The article discusses the colloquial formula I Vam ne khvorat! – widely used among native speakers of Russian, little known to foreigners and possessing mixed pragmatics: greetings, farewells, toast proposals, and well-wishing. Usually this formula "works" in Russian-language communication according to the "boomerang rule" (Bud' zdorov! – I vam ne khvorat'!), but sometimes the same expression is used and perceived in the act of communication with "exactly the opposite". In such situations, this formula becomes a response to rudeness (Idi na kh*y! – I vam ne khvorat'!), and sometimes it is perceived as offensive (Idite, bud'te zdorovy! – I vam ne khvorat'! – A vy yeshcho i kham vpridachu, kak ya poglyazhu). The study was carried out on the material of contexts from the National Corpus of the Russian Language (oral, main and newspaper subcorpora), as well as from the Internet. An analysis of the usage and perception features (primarily by native speakers of other languages, for which a special linguistic survey was conducted among Chinese respondents) of this formula seems important both for modeling the communicative behavior of the Russian-speaking society and for preparing foreigners for communication in this society.