This article analyses the typical features of the influence of the Russian language on Belarusian stage speech. Contemporary theatre, concerts, and other cultural events have played an important role in the popularization in the Belarusian language of misbalanced bilingualism. According to the transcripts of modern actors, emcees, and musicians recorded in theatres, music clubs, literature museums, and culture centres between 2012 and 2019, different fragments and types of mixing of Belarusian and Russian are revealed. Firstly, we notice switching of language code, which is used for famous phrases from literature, cinema, etc., or shows someone else’s speech. Secondly, we have examples of Russian language interference in Belarusian at the lexical, grammatical, and phonetic levels. So-called trasianka-distorted Russian language according to the special features of the Belarusian orthoepyis observed as a specific kind of interfered speech. In addition, various variants of hard mixing of systems and subsystems, functional styles of two languages (especially including of dialect words and forms), jargon lexis, and special units of alternative norms of the Belarusian language tarashkevitsa are shown. This research notes that mixed speech is a result not only of bilingual interaction, but the decline in the standard of stage speech. It is noted that trasianka helps to create a comic or negative character image on stage.