Gender harassment is prevalent in contexts where women are underrepresented and negatively stereotyped, yet instances of gender harassment are often discounted as unimportant and inconsequential. The current research presents an examination of gender harassment operating on a male-majority university campus in the form of a sex-based slur known as the “Princess Syndrome.” Across two studies, the present research investigated the prevalence, meaning, and adverse consequences of the label. Study 1 indicated that the label was widespread at the university: 70% of participants had heard of the label, nearly half had used the label, and 1 out of 4 female participants had been targeted by the label. Inductive content analysis of open-ended responses revealed that the label was a derogatory term used to insult and degrade women by stigmatizing women as manipulative, exploitative, and stuck up. In Study 2, participants read about and rated a female student who was either labeled with the “Princess Syndrome” or not. Consistent with predictions, participants were more likely to discount the female student’s success in an engineering course as due to external factors (e.g., luck), rated her as less competent, and were less likely to choose to work with her on a team project when she was labeled with the “Princess Syndrome” than when she was not labeled. Results contribute to a growing body of literature demonstrating that sex-based slurs matter and suggest that slurs such as the “Princess Syndrome” may constitute a consequential yet understudied source of gender harassment for undergraduate women in STEM that reinforces and maintains gender inequity.