This article contributes to the changing landscape of fieldwork practices within sociolinguistic research, specifically the practice of online ethnography. It makes a case for the significance of online chats in observing the construction of ethnic identities and social intimacy among young Malaysian English (henceforth Manglish) speakers. The rise of Manglish discourse has been hardly ignored in digital settings. Thus, the rationale for choosing Manglish as a language of communication within online spheres such as Instant Messaging is unclear. This article argues that the socially structured meanings that underlie Manglish practices deserve exploration as it would benefit from online ethnography. Drawing on Androutsopoulos's (2008) discourse on online ethnographic approach, this paper shows how researchers could use WhatsApp chats to explore the linguistic and social behaviour of Manglish speakers. The findings suggest that the interrelation of speakers' online behaviour and linguistic choice can denote their ethnicity, in-groupness, stances, and regional identity. Online ethnography is therefore significant and should not be limited to linguistic sources but also used as a mode of participating in, as well as observing, the construction of identity that reflects the 'offline' aspect of speakers' social lives.