English development in the digital age increasingly unfolds within the
dynamic, multimodal spaces of social media rather than exclusively in formal
classrooms. Yet, empirical evidence detailing how specific digital linguistic
features influence adolescent learners in non-Western EFL contexts remains
limited. Addressing this gap, this study investigates how Indonesian senior
high school students adopt and integrate informal English expressions such
as slang, acronyms, abbreviations, and hashtags from social media into their
communicative practices. Using a mixed-methods descriptive design, data
were collected from 66 students through a structured questionnaire, open
ended items, and semi-structured interviews. The findings reveal four key
patterns: (1) frequent and habitual use of English across digital platforms; (2)
significantly increased confidence supported by low-pressure, asynchronous
interaction; (3) systematic and purposeful adoption of informal linguistic
features for expressiveness and social alignment; and (4) cross-contextual
migration of digital expressions into offline communication accompanied by
register awareness. These results indicate that social media operates as a
parallel linguistic ecosystem that fosters communicative agency, pragmatic
flexibility, and identity construction rather than linguistic deterioration. The
study’s originality lies in its empirical focus on concrete digital linguistic
forms within a secondary school EFL context in Indonesia, a setting
underrepresented in prior scholarship. By reframing informal digital language
as an adaptive communicative resource, this research contributes to
discussions on informal digital learning of English and offers pedagogical
implications for integrating students’ digital repertoires into context-sensitive
English language teaching in the broader global EFL landscape.