Business negotiations constitute a key element of supply chain interactions that can create additional value for both the buyer and supplier. However, negotiations can also render the parties vulnerable to deception. While a large body of knowledge on buyer–supplier relationships exists, research on deception and bounded ethicality in supply chain relationships is still nascent. We advance this new research stream in behavioral supply chain management by first conceptualizing two types of deception—bluffs and lies. Departing from previous content‐dependent conceptualizations/definitions, we define both as convention‐dependent, norms‐based constructs: Bluffs (lies) are deceptions that are palatable (unpalatable) to both parties in a buyer–supplier negotiation. Second, studies 1 and 2 of our article employ Q methodology and best–worst scaling to operationalize bluffs while refining the construct of a lie. Third, a correlational study (study 3) examines the psychological properties/cognition of a negotiator who lies, bluffs, or does neither (i.e., communicates honestly). Fourth, a behavioral experiment (study 4) investigates the psychological consequences of bluffs, lies, and honesty for the targets. Bluffers (liars) show low (high) degrees of moral disengagement. Targets of bluffs experience high degrees of self‐directed anger but are willing to engage in further negotiations with the bluffer, while targets of lies experience high degrees of anger directed at the liar and show a low willingness to further negotiate with the liar. Taken together, these findings provide new insights into the dynamics of bluffing and lying in buyer–supplier negotiations.