Studies on humour in Nigeria have been extensively carried out from the perspectives of stand-up comedy and computer-mediated communication. There is a dearth of scholarly enquiries on humour in situation comedies (sitcoms). This paper investigates humour in the interactions of characters in Jenifa’s Diary and Professor JohnBull, with a view to accounting for the manifestations of humour, the humour strategies deployed and the functions that the humorous utterances serve in the sitcoms. The work is situatedin Culpeper’s Impoliteness Theory. Eight excerpts from the sitcoms were subjected to pragmatic analysis. Two discourse functions of amusing and castigating are discovered in the data. The former serves the function of facilitating discourse and changing presumed power and status, while the latter serves the function of maintaining one’s own space and autonomy, and demanding respect. Allusion, parody, retort, tease, banter and put-down are the humour techniques employed in the sitcoms. The study corroborates the claim of earlier studies that humour in every sphere of language use serves certain functions beyond the interactional need to create amusement.