This chapter focuses on the notion of particularized conversation implicatures. It starts by illustrating these implicatures with the case of metaphors, and shows the different ways in which Grice and relevance theory accounted for them. It goes on to argue that neither framework is equipped to explain why speakers use implicatures to communicate. The chapter presents a possible explanation for the existence of implicatures in terms of plausible deniability. Finally, the chapter introduces the notion of epistemic vigilance, a mechanism that hearers develop to avoid being deceived or manipulated.