Young people involved in climate justice activism engage in a range of tactics across entangled 'online' and 'offline' spaces. This article explores the affordances and ambivalences of humour in digital modes of contention for young people (aged 12-30) involved in climate justice activism. Four of the authors are 19-22 years old and involved in climate justice activist organising, and one author is a university-based researcher in her early 40s. Through a collaborative, intergenerational analysis of stories of hybrid digital climate activisms, we ask: what is the role of humour in young people's varied activist repertoires? Thinking with the conceptual resources of adrienne maree brown's "Pleasure Activism," we pose three analytic provocations: (i) humour can amplify generational tensions; (ii) humour is entwined with individual and collective identity-work; and (iii) sometimes humour is 'just a thing' (that can also help with burnout). We collaboratively analyse how young people use humour to dissent, through lampooning hierarchical power structures and profit-driven systems, drawing attention to intersectional injustices, and joyfully expressing affinity and solidarity. At the same time, humour may exclude, offend, and reinforce existing divisions and injustices. Humour is an underappreciated feature of organising towards a more just world, even as the pleasurable and just outcomes of humour are not guaranteed. We argue for further attention to young people's multimodal repertoires across hybrid spaces, and the multiplicity of feelings that accompany climate justice activisms.