Conflict and rivalry are among the main reasons why human beings form groups and they determine what goes on within and between groups. However, why is threatening competition such a strong driver of brand community? How, where and why does rivalry or oppositional loyalty manifest itself within and between brand communities? A netnographic study addresses these research questions by drawing on social identity, social comparison, self-categorization and brand culture theory among Ford and Holden (GM) communities in Australia. Findings suggest that rivalry between brand communities overtly manifests itself in the form of humor, epithets and ridicule for the most part, but also tips over into malice and outright hostility on occasion. While the underlying rivalry and conflict are continuous (and deep-rooted), certain events and occasions serve to heighten latent tensions between communities. Another unique dimension to this particular brand rivalry is vicarious alignment with one or other community even from non-users of either brand.