Expressive words are marks of cultural identity as they differ among people. They are conventional in each linguistic community and therefore need to be considered in the context of teaching/learning of a second language for foreigners as they constitute important elements of communication. This paper presents, analyses and classifies according to stylistic and functional criteria the contextual use of a set of onomatopoeic and non-onomatopoeic expressive words observed in the daily informal speech of the Rio-São Paulo axis within the period between August, 2003 and May, 2006. From the occurrences that constitute the corpus described in the paper, one can notice a wide range of functional and semantic variation of expressive words reflecting the ability of Brazilian people to cope with context in a high level of abstraction. One can also observe that these words reveal uncountable aspects of the Brazilian subjective culture.