Incidents of humour in the radio commentary of rugby union provide an example of semi-spontaneous humour that exists between informal conversation and professional performance. This is exemplified in analysis of the reporting, both quantitative and qualitative, of two teams of commentators providing commentary on the same three rugby union test matches. In order to account for the formal qualities and broadcast nature of this humour, the analysis develops a mixed method approach that combines quantitative analysis with both literary and conversational approaches to humour. The resulting analysis suggests that micro communities of practice evolve their own patterns of use for humour that draw on a common pool of strategies. It is argued that this particular form of conversational humour is best understood in relation to the social and cultural context of its broadcast, rather than in terms of the interpersonal dynamics of the participants.