The word of Pagerwesi is derived from two words: pager (fence) and wesi (iron). Pagerwesi literally means the day of "iron fence". The Hindus religious suggestion is that one should surround oneself with a strong fortification against the forces of evil.
The Pagerwesi day is also a day upon which an ancient battle between good and evil is celebrated.
I hope there's not really an ancient battle between good and evil today. My head hurts.