This article examines the impact of the sociodemographic profile (including age, gender, and educational track) of Flemish adolescents (aged 13-20) on lexical aspects of their informal online discourse. The focus on lexical and more "traditional," print-based aspects of literacy is meant to complement previous research on sociolinguistic variation with respect to the use of prototypical features of social media writing. Drawing on a corpus of 434,537 social media posts written by 1,384 teenagers, a variety of lexical features and related parameters is examined, including lexical richness, top favorite words, and word length. The analyses reveal a strong common ground among the adolescents with respect to some features but divergent writing practices by different groups of teenagers with regard to other parameters. Furthermore, this study analyzes both standardized versions of social media messages and the original utterances (including nonstandard markers of online writing). Strikingly, different results emerge with respect to adolescents' exploitation of more traditional versus digital literacy skills in relation to their sociodemographic profile, especially with respect to sentiment expression (verbal versus typographic/pictorial). The study suggests that the inclusion of nonverbal communicative strategies, for instance in language teaching, might be a pedagogical asset, since these strategies are eagerly adopted by teenagers who show proof of less developed traditional writing skills.