Public concern about “gaslighting” has increased significantly in recent years, both in sociology and the public imagination. As well as describing abuse in romantic relationships, the term has provided a lens for popular understanding of ‘post-truth’ politics. Given that metaphors influence how problems are conceptualised and responded to (Lakoff and Johnson, 2003), we ask how “gaslighting” shapes popular responses to disinformation on Twitter and the conspiracy-rich 4chan. We find that discussions of gaslighting have increased significantly on both platforms between 2020-2021, and spike during the week of the United States 2020 election. We find the metaphor can powerfully contest disinformation, while at the same time spread self-sealing and self-fulfilling anxieties about deception that are resistant to disagreement. In light of these findings, we consider how a well designed and well intentioned “good echo chamber” (Pohlhaus 2020) might constitute a technique of resistance to online disinformation.