We explore how norms of science are given attention through laughter in life science doctoral supervision. Four supervision sessions were observed and video recorded. All laugh units were identified, and instances of humour were coded in relation to norms of science. Our analysis reveals tensions around how to do valid research, governance vs. administration and the willingness to make sacrifices. Balancing between validity and feasibility and between quality and quantity, not to mention the importance of scepticism in intellectual conversation, are other important norms of science highlighted in the interaction. We found that norms of science are a vital part of life science supervision and that supervisors play a critical role in the process of socialising PhD students into becoming researchers. We saw how PhD students are taught to navigate these norms, that is, how they are supposed to behave in these complex normative systems. We recognised that the norm of calling has many benefits for researchers in natural science but may pose a threat to good work–life balance for PhD students. Since humour is a powerful form of communication, we recommend that supervisors reflect on how laughter is used as well as which norms and values they teach.