In the foot massage industry,"edge ball" usually refers to a marketing strategy that uses words or plots related to prostitution to promote or promote without violating relevant laws and regulations. This kind of marketing strategy often made foot baths similar to erotic places in some aspects, but it did not directly violate the relevant laws and regulations. For example, some foot massage places might use words such as "massage table" and "erotic massage" to promote themselves, but the actual service would not involve any erotic content. This kind of edge ball marketing strategy could allow the foot massage place to operate legally and attract more customers at the same time.