The Bulgarian traditional beliefs define the 2 weeks after Xmas as the time of various evile spirits -- vampires, 'talasumi' (ghosts), samodivi (evil women spirits), and other demons. This is the time between the birth of Jesus and his baptising. During this period the evil spirits leave the underworld to terrorise the peaceful folk.
These days are called 'mrusni' (dirty) or 'poganni'. For two weeks everyone should go home before dark to avoid becoming victim of the assorted evils. Christenings, weddings and wakes are not held for the same reason.
Instead, the dirty days are for rest and partying. Women shouldn't do household work apart from making and clearing the table. They shouldn't tidy up, weave, sew, etc. Men should also do no work apart from feeding the livestock.
During the two weeks, the vilages are protected by the 'kukeri'. They wear scary clothes & masks, and carry big bells to frighten the evil spirits & illnesses away. The masks are either of various animals or of a typical character - devil, priest, bride, or a black man. Only the 'bride' is allowed in the house to ritually sweep out the evil spirits and illnesses. The hosts give money in return.
IN some houses, the young recently married women are 'stolen' and hidden, because this will bring rich harvest. Then the 'kukeri' chase the 'thieves' and the hosts pay double ransom.
Note: in some areas of Bulgaria, the Kukeri ritual is performed just before Spring.