Cockroaches are not known to crawl into the human private parts, such as the vagina or penis, as they tend to avoid areas with movement and light. While it is theoretically possible for a cockroach to crawl on a person's skin, including the genital area, it is extremely rare for them to enter these areas. However, if a cockroach were to come into contact with the genital area, it could potentially bite or sting if it feels threatened or provoked.