This paper claims that idiomatic expressions play a very important role in the protagonist’s speech characteristics in Ilf and Petrov’s novels. Phraseologisms used in a criminal sense are either the author’s neologisms treated in the style of criminal slang or idiomatic expressions corresponding to criminal topics. Two of these phraseologisms clearly belong to criminal slang. Comic effect is reached by the manner of their use in context. As a result of this, they cause even more problems for translation. Apart from these objective moments, the translator’s artistic sense and linguistic sense of humour are also significant factors.