This chapter explores innovative forms of political communication among citizens on Twitter, in the context of the 2017 French Presidential Elections. It notably questions the degree to which ‘contagious’ social network communication may be impacting discourse on politics in the public sphere, related to the debate around ‘fake news’. From a corpus of over 50M election-related tweets, the chapter identifies those which were most widely retweeted during the second round of the French elections. Through qualitative analysis of 197 manually coded ‘viral’ tweets, it seeks to characterise their contents in this particular context, in order to fill a gap in the literature and better understand how the contents, tone and subject matter of tweets may be related to virality, thus helping identify the characteristics of viral political tweets as an innovative and influential form of political communication within the media-related public sphere. The study finds little evidence of ‘fake news’ in the corpus studied and highlights instead practices of whistleblowing, but also a dominance of non-factual, opinion-based commentary, as well as humour, irony, satire, parody and mash-ups. In discussing these insights into the mechanics of viral communication, the chapter underlines both specific innovations linked to the technological medium and continuities with traditional offline practices, and suggests that popular contents on Twitter tend to feed into discourse discrediting politicians rather than supporting inclusive democracy.