Visuals are generally considered to be rich in information, but also to be open to many different interpretations. As a consequence, many argumentation scholars doubt that visuals can constitute argumentation (e.g. Fleming, 1996; Johnson, 2003, 2010; Patterson, 2010). In this paper, we argue that the rhetorical and argumentative potential of visuals and multimodal texts is strengthened if they belong to recognizable genres, genres being governed by discourse-internal factors as well as situational/pragmatic understanding. The genre of traffic signs can draw on specific genre conventions thanks to these signs’ highly coded nature. As a consequence, traffic signs constitute an exemplary category to make the point that visuals and multimodal texts can function rhetorically or even argumentatively. We support our claim by first analysing a number of unusual instances of the genre and then discussing a few visual and multimodal signs whose argumentative potential no longer depends on specific traffic-related circumstances but crucially depends on the pretence that they are traffic signs.