Ina Kere (means small fire) was once the headmistress of a prominent school in the old Oyo kingdom in Yoruba land. She was of course very strict and puritanical, as her name implies. So on a hot day the students of her school grew tired of their Headmistress' wrath and hesitantly dared one amongst them to retaliate.
It turned out to be the headmistress' little son who was instructed to steal his mother's shoe. Unfortunately, he was successful and all the students knew this when they could hear cries of pain. The hot afternoon ground scorched the Headmistress' feet as she looked for her stolen shoe. It turned out that hearing his mother's cries the headmistress' son fled into the forest nearby for fear of a swift and painful reprimand.
In time the boy did not return, and a determined and angry Headmistress Ina Kere followed in search of her lost son all the while calling out. They never returned, and it was said that hunters and travelers over the years could hear cries of anger slowly turn to cries of sorrow.
Till this day kids in Nigerian schools (especially kids in boarding houses in the middle of nowhere) hear the spirit of Headmistress Ina Kere, (which she came to be known as) calling out to her lost son all the while the eerie, paralyzing 'koin koin' sound ringing from her one shoe as she slowly wanders through the night. Today she is popularly known as Madame Koin Koin.