How does the analysis and evaluation of argumentation depend on the dialogue type in which the argumentation has been put forward? This paper focuses on argumentative bluff in eristic discussion. Argumentation cannot be presented without conveying the pretence that it is dialectically reasonable, as well as, at least to some degree, rhetorically effective. Within eristic discussion it can be profitable to engage in bluff with respect to such claims. However, it will be argued that such bluffing is dialectically inadmissible, even within an eristic discussion.