This was, and still is, a practice of merriment and fun among Norwegian young people, that took place during the happy holiday season between Christmas (Jul) and New Year.
A group of young people would dress in old clothes, or exchange clothes with their friends or perhaps parents, then put on masks, or wrap scarfs about their faces, and then as darkness fell they would go to a home in the neighborhood to see if the folks in that house could guess who these Julebukkers were. Various attempts would be made by the people in the visited home to make the masked visitors reveal their identity, such as try to trick them into saying some words, or to laugh, or give some other clue, maybe to guess their identity by their clothes.
When the guessing was over, whether successful or not, there would be refreshments served, and a brief visit, then off to the next home by the masked group, likely accompanied by the young people of the just-visited home. After a couple hours there could be quite a large group of youngsters out having fun in this way.
This Julebukking found its way over here to America also, and there was some of it still going on here in the West Prairie area into the 1940's. It is still being done in Norway, in the 1980's.
Here on the prairie it seems that the Halloween trick or treat has taken the place of Julebukking.
Allen Osmundson
Source: Cooperstown, North Dakota 1882-1982 Centennial page 51