Abstract This paper analyses a snapshot of a conflictive Greek YouTube polylogue dealing with the issue of public online female nudity and the norms pertaining to both the act itself and its verbal critique. The said polylogue contains a markedly high proportion of lay (im)politeness/(in)appropriateness evaluations ( Locher and Watts 2005 ). By quantifying and critically analyzing key lexical impoliteness ( Culpeper 2011 ) and metapragmatic markers contained in the evaluations, I identify the ways in which the norms of online verbal behaviour are discursively negotiated amongst the polylogue participants, focusing especially on the arguments and justifications underlying the suggested norms. It is found that, firstly, the notions of (im)politeness/(in)appropriateness emerge as open to fierce, yet heavily argument-supported discursive dispute; secondly, sexualized slang functions both as an object of critique and as an extremely versatile rhetorical instrument serving metapragmatic argumentation; and, thirdly, online (im)politeness/(in)appropriateness is construed not as a superficial matter of netiquette, but as a deeply ethical and political-ideological controversy, especially regarding speech liberty and political correctness.