Impolite and aggressive behaviour of anonymous users appears to be an important feature of online newspaper comments. This paper identifies and investigates how impoliteness is utilized strategically by newspaper readers to attack the author of an article. Empirical data is drawn from “Have-your-say” sections of the Guardian Online, Times Online and Telegraph Online. Results illustrate that impolite moves frequently involve face-threats that question the journalists’ authority, credibility and trustworthiness. In the main part of the paper a categorization scheme for different types of impolite moves is introduced and a working definition of impoliteness in the context of “Have-your-say” sections presented. After having sketched a number of fundamental methodological and theoretical challenges in impoliteness research, the paper also demonstrates how the communicative setting and medium influence the realization and interpretation of impolite behaviour in those forms of public debates. Given the challenge of identifying and conceptualizing impoliteness in general and more specifically in a computer-mediated environment, netiquette rules prove especially useful for norms of appropriateness. It is also argued that the strength of those face-threats may be boosted by the fact that they are uttered in front of a large audience and more specifically the journalist’s readership.