Tiyanak is a creature from Filipino folklore that is said to be a baby-like being with sharp teeth and evil intentions. Many people believe that these tiny creatures are the souls of children who died before they were baptized. They are known for their mischievous behavior, such as luring people into the forest or sucking the blood of animals and infants.
Some people believe that tiyanaks can be dangerous and are best avoided. Others believe that they can be appeased with offerings and prayers. Tiyanaks are often depicted in popular culture, such as in movies and TV shows, and are a common theme during Halloween and other festivals in the Philippines.
So basically, a tiyanak is a scary creature that looks like a baby and can do bad things if you're not careful. People talk about it a lot in the Philippines, especially during spooky times like Halloween.