The story is of Romanian descent that dates back to the 1500s. It was used by parents as a way to keep children from sneaking out or acting up.
There once was a woman named Alina Patkavior, the daughter of the village witch. On her deathbed, the witch gave Alina an amulet and a hex: "By the Belly of the Snake, May those that mean to harm me be put to death."
One day a group of bandits raped her and left her in the woods to die. Alina awoke took the amulet and said the words summoning the demon Din Burta de Sarpe. The demon destroyed the men that attacked Alina in exchange for the child that the bandits had left in her womb. When the time came for the Demon to claim it, she could not give him up breaking her promise. The Demon then cursed the Patkaviors who would be infertile forever.
Alina's son grew into a young man. On his mothers deathbed, Alina shared that fatal night with him, passing the amulet knowing he may be the only one to lift the curse. Desperate to produce a child with his wife he called the demon and begged it to lift the curse.
The demon said he could not undo what had been done, if he wanted a child he would have to bloody his hands to take one. However, as soon as the child was named a Patkavior, it would join the curse and be unable to produce another child. He did as he was bid and cut a baby from its mother's belly.
For generations, the Patkaviors continued this ritual driven by the demon to carry on their family name.