“Mang-tae-gi-hal-a-buh-ji will come kidnap disobedient children!” (말 안 듣는 아이는 망태기 할아버지가 잡으러 온다!) is a phrase that makes all Korean children shiver in fear. Mang-tae-gi-hal-a-buh-ji means grandpa (hal-a-buh-ji) of net bag (mang-tae-gi). The net bag was widely used during the pre-modern times and is made from weaving hay together like a net, making a tightly knit bag for carrying goods such as crops.
There are stories of the Mang-tae-gi-hal-a-buh-ji kidnapping children either to scold them and return them back, never let them return or cannibalizing on them. It is commonly thought that the origin of the Mang-tae-gi-hal-a-buh-ji is of old men that were leprous carrying the Mang-tae-gi bag. There was a belief of being able to be cured of leprosy through boiling and eating a child.
I collected this from my mother, who has numerously used the name of Mang-tae-gi-hal-a-buh-ji in the past in order to get me to become more obedient. This is significant to my mother has herself has also been subjected to this superstition by her own mother. My grandmother, despite being a devout catholic woman, made sure to track all superstitions to keep my then unborn twin cousins safe from harm. One of them involved giving the yet to be born child no pre-birth name (태명/ Tae-myeong) or intentionally giving them a very bad pre-birth name. This was because of the superstition of when one gives a good pre-birth names to children, evil spirits that are around, including Mang-tae-gi-hal-a-buh-ji, will try to inflict harm on the good child. By downplaying the child through a bad pre-birth name, one is able to avoid the attention from these unwanted evil spirits. My twin cousins were given pre-birth names of Ddol-ddol-I (똘똘이) which means someone that is somewhat bright. Not the worst, but not good enough for evil spirits I guess.
Mang-tae-gi-hal-a-buh-ji can be compared to the Boogeyman, another mythical creature that is used to frighten children into good behavior. By instilling fear of disobeying, the parents can control the child much easier. However, despite using the name of Mang-tae-gi-hal-a-buh-ji to scare children, the parents themselves also take caution against the evil spirit by taken on traditions such as giving no pre-birth names or bad pre-birth names.