This article brings the critical turn in linguistics—with its current scepticism towards essentialised languages and bias for languaging—under critical evaluation. It does so by bringing it face-to-face with the local-knowledge turn in sociolinguistics that investigates local knowledge and local epistemologies, held by language users themselves, to understand sociolinguistic phenomena. This article analyses whether and how the epistemologies inherent to language, mother tongue, and languaging hold relevance in local metalinguistic talk in Malaysia. Focus group discussions with ethnic Malay, Chinese, and Indian youth reveal that languaging through Bahasa Rojak is already firmly embedded in local epistemologies for communicating across ethnolinguistic divides and fostering interethnic inclusiveness. An essentialised view of language, however, remains vital to any holistic sociolinguistic research in Malaysia in culturally specific ways that do not conflict with languaging. The article therefore supports arguments that we ought not to disregard mother tongues in the interests of critical linguistics. (Critical linguistics, mother tongue, languaging, linguistic culture, Malaysia, folk linguistics)*