Employees sometimes engage in uncivil behavior in the workplace. We ask (1) How commonly do customers witness an employee behaving uncivilly? (2) What negative effects does customers’ witnessing of an employee’s uncivil behavior have on customers and firms? (3) Why do these effects occur? The results of three studies suggest that it is not uncommon for customers to witness an employee behaving in an uncivil manner. It occurs in many industries. Moreover, witnessing such behavior makes customers angry and creates desires to get back at the uncivil perpetrator and the firm. These effects occur even when a manager’s uncivil comment is aimed at correcting a subordinate’s job-related offense and even when it is delivered offstage, outside of the customer servicescape. Finally, we demonstrate that these effects are driven by customers’ concerns about deontic injustice from incivility (reaction to a wrongful misconduct that violates fairness standards). These results contribute to the literature on workplace incivility and customer reactions to service encounters as well as the burgeoning literature on customer anger and revenge. We suggest that organizations invest in training programs focusing on employee civility. Managers should receive training in coaching to mitigate against the detrimental effects of incivility.