This paper approaches teasing as one of the most ambiguous types of conversational humour. Based on the teasing episodes found in the British National Corpus, it proposes different categories of doing teasing, its functions and the target’s reactions. The results show that with the help of teasing, most often the teasers decide to conceal their genuine criticism levelled at the targets or point to some behavioural or personal deviations, while the targets tend to react seriously or refute such teases. Therefore, it is argued that teasing should not be seen as an extremely relationship-affirming verbal practice, but can easily occasion a spectrum of evaluations from politeness and impoliteness to mock politeness and mock impoliteness.