Research suggests that mystery products can be appealing to consumers and can motivate interest and purchase. In this paper, we examine a different benefit of these offerings—their effect on driving conversation. We propose that such products can prompt a conversation due to their ability to motivate joint speculation, or the process of thinking about possible resolutions of the uncertainty with others. We define this novel driver of conversation, delineate it from related constructs, and situate it in the literature. We then provide initial evidence for the proposed theory in seven studies (n = 2835), demonstrating that mystery products increase the desire for conversation (Studies 1, 3–4, Supplemental Studies A–C) and generate joint speculation (Studies 2–4, Supplemental Study B–C). We also rule out alternative explanations (such as information acquisition and savouring, Study 3; novelty, Supplemental Study B). These effects, however, are attenuated for closed‐minded consumers (Study 4), who are less open to considering multiple perspectives and thereby less interested in joint speculation. We conclude with directions for future research and implications for marketers.