Abstract A reflection of both the intensity of sharing practices and the appeal of shared content, the term ‘viral’ is often seen as coterminous with the digital media age. In particular, social media and mobile technologies afford users the ability to create and share content that spreads in ‘infectious’ ways. These technologies have caused moral panics in recent years, particularly within heavily regulated and censored media environments such as the People’s Republic of China (PRC). This paper uses the spread of a ‘viral’ sex video among young Chinesespeaking people who live transnational lives between Japan, China, and Taiwan, to reflect upon the question of ‘viral’ media as it is conceptualised more broadly. Their position both inside and outside Sinophone mediascapes affords a useful case study to think beyond purely institutional discussions of Chinese media, and focus on the ways media practices, affects, and affordances shape patterns of content distribution. It examines the language and practices of ‘virality’ among Chinese-speaking people in Tokyo and shows how the appeal of content like the sex video ‘digital stuff’ on WeChat are typically a digital amplification of pre-existing social practice. Described in terms of ‘sociothermic affects’ (Chau 2008) such as ‘fever’ and ‘heat’ (re/huo), the infectious nature of media is imagined in different but commensurate forms of virality that precedes the digital age. In the digital age however, virality is also made scalable (Miller et al. 2016) in new ways.