The fact that women wrote more graffiti with sexual content might be explained by the SIDE-model which states that breaking with social norms is easier in groups or in situations of total anonymity

He writes a lot, she gets to the point - sex differences in bathroom graffiti. Kathrin Masuch, Susanne Schmehl, Elisabeth Oberzaucher. Human Behavior and Evolution Society 31st annual meeting. Boston 2019. http://tiny.cc/aa1w6y

Abstract: Graffiti might be seen as a special kind of art or vandalism, but they are a special way of communication. Public bathrooms are most suitable for research on graffiti as they offer privacy and shield from the influence of other persons. Earlier research on graffiti showed that women are not as likely as men to create graffiti. Robin Dunbar claimed that the content of gossip is based on evolutionary strategies. Therefore, females tend to talk about social interactions and support, whereas men are more likely to verbally intimidate possible competitors. We examined 165 bathrooms in restaurants and bars and classified 4747 graffiti. We picked locations of high variability to ensure high social and educational diversity of visitors. Data analysis revealed a number of sex differences. Graffiti conveying social information and sexual content are found more often in ladies’ bathrooms, but generally, more graffiti are found in men’s rooms. The results partially support earlier findings but also raise new questions: The fact that women wrote more graffiti with sexual content might be explained by the SIDE-model which states that breaking with social norms is easier in groups or in situations of total anonymity.