This paper unravels the presence of humour in prison as an institutionalized aspect of prison life. The analysis shows how officers use humour to manage their relationships with prisoners and other staff, and how they make use of humour to establish a collective understanding of the officer job, crafting themselves as a group. The humorous exchanges between officers, prisoners and other staff facilitate social spaces where officers briefly meet prisoners as equals, and where staff articulate hostility towards one another. These social spaces exist as briefly as the humorous exchanges, but the implications are real. The officer–prisoner joking relationship fosters conflict avoidance, smooth daily interactions, service provision for prisoners and transgression of officer norms for camaraderie. In contrast, the staff–staff joking relationship grants officers a sense of power vis-à-vis other staff and an opportunity to articulate hostility where staff solidarity is required. As a communication device with ambiguous qualities, humour unites the real and the unreal, shapes social structure, interaction and positioning and is suitable for identity work in prison.