There are primarily two discourses on slang: one is based on the Linguistic Purism View (slang is seen as an ugly, poor and/or dirty vocabulary); and on the other hand, the Socio-historical-cognitive view understands slang as a rich component of language (BARRA, 2007; MATTIELLO, 2005; ZARBALIYEVA, 2012). Taking this into consideration, this qualitative and hermeneutic study aims at investigating which ideology lies in the discourse of two high school English teachers in Brazil. Furthermore, the focus of this study is also on investigating the possible implications of that ideology for the English classes in the Brazilian context. For the aforementioned purposes, the teachers were interviewed and their discourses were analyzed under the Critical Discourse Analysis approach (MACHIN; MAYER, 2012), more specifically based on the Sociocognitive approach (WODAK & MEYER, 2009). Results show that the teachers' discourses are shaped by both perspectives (Linguistic Purism and Socio-historical-cognitive perspective). As a consequence, the use and the teaching of slang in Brazil are limited because of several reasons, especially concerning its semantic field.