Recently, a public restroom in a commercial street in Wuhan has sparked heated discussions due to the use of the "concave convex" symbol to distinguish between men and women. The design was noticed and criticized by netizens for being "uncomfortable", and subsequently the related signage was quickly replaced with more conventional male and female simple strokes. This incident has once again sparked discussions among netizens about the design of public facility signage and social perception. The primary function of public restroom signage is to facilitate quick identification of gender and address "physiological needs", rather than causing ambiguity or discussion. Although "concave convex" has a pictographic meaning, it clearly lacks universality and intuitiveness in practical use, and may even confuse and inconvenience people during the "three urgent" situations. This design clearly deviates from the functional essence of public signage. In addition, the design of signage in public spaces not only requires practicality, but also needs to consider cultural sensitivity and social identity. The design of "concave convex" may carry negative metaphors in specific contexts, causing discomfort for some people. This also reflects that public design cannot blindly pursue so-called "creativity" or "uniqueness", let alone ignore the feelings of the user group. Especially in multicultural environments, design should avoid expressions that may cause ambiguity to avoid controversy and negative social impact. And the country has always had clear recommended standards for public signage. Although not mandatory, it still provides clear reference for design. Designers should pay more attention to the functionality of signage, rather than simply pursuing novelty and personalization. Public facilities are designed to serve everyone and should respect diverse social needs, following the principles of clear functionality and concise expression. Although the toilet signs are small, they reflect the deep issues of humanization and standardization in the details of public services. I hope similar events can provide reference for future public design, making every detail more in line with public needs and reflecting respect for social diversity and individual feelings. (New Society)