The Siguanaba's mythic origin tells the story of Sihuehuet, a beautiful but vain and cruel peasant woman who used her charms to seduce princes and warriors, neglecting her duties and her own son, Cipitío. The god Tláloc, enraged by her corrupt maternity and libertinage, cursed her: 'You will be beautiful from a distance, but abominable up close. You will attract men only to horrify them, and you will never find love, only fright.'
Since then, the Siguanaba roams the ravines, public water tanks, and riverbanks, preying on 'donjuanes', drunkards, and the unfaithful. She appears at night, always with her back turned or her face hidden by her long, black hair. Her method of hunting is specific: she beckons men with her beauty, only to reveal her true, horrifying form when they finally catch up to her, leaving them devastated, often to the point of death or madness.
The Siguanaba serves as a guardian of domestic morality, punishing male irresponsibility by transforming the object of desire into an object of absolute horror. Antropologically, she fulfills a clear function of social control, particularly in rural societies where men's behavior endangered their families' well-being. To defend against her, tradition offers strange methods, including biting a machete, making the sign of the cross, or insulting her vanity.