It has become standard practice for consumers to customize products instead of choosing off-the-shelf solutions. A new practice is that consumers can directly share and discuss their customized products with their peers via social product configurators. We examine how the type of communication affects peer decision-making and satisfaction in such configurators. Drawing on research on mass customization, electronic word of mouth, and narcissism, we propose that narcissistic communication is crucial to understanding the effect of a shared configuration. A series of three studies demonstrates that consumers scoring high (vs. low) on narcissism are more likely to share their customized product online as a sample configuration and to use I-centered communication to describe that configuration. Such narcissistic communication makes peers adjust their own customized product to the sample configuration and to evaluate their own product less favorably. These findings suggest that narcissistic communication influences consumers’ decision-making by increasing the likelihood to conform, potentially negatively impacting consumer satisfaction. The social power of narcissists has implications for both marketing research and practice.