Written chatspeak is basen on two principles: (1) write like you speak and (2) write as fast as possible. As for Flemish chat language, the first principle appears to lead to a multilayered mixed code, in which dialectical, substandard Flemish and standard Dutch features interact in an eclectic way. Most of the chatters additionally insert English words in their chat discourse as well. This intensive code mixing is presumed to be – at least to a great extent – a reflection of the daily speech of these Flemish chatters. But how reliable is this assumption? Can chatspeak serve as an alternative dataset for the study of (spoken) language variation and change and thus as a research tool for e.g. the study of Flemish teenage talk and the representation of non-standard speech in spoken interaction? The dependent variables for the present test case are two substandard Flemish (or ‘tussentaal’) features that incite the chatters to break the second principle, as their use includes utterance extension. The main question is whether the second principle impedes the use of these substandard forms in Flemish chatspeak. And can we distinguish English insertions that are elicited by the chat medium from English insertions that are not?