Some Danish New Year's Eve revelers traditionally smash plates against friends' doors for good luck.
The custom involves saving or collecting unwanted dishes and breaking them outside the homes of friends, relatives, or neighbors. A large pile of broken crockery at a doorway is traditionally interpreted as evidence that the household has many loyal friends.
The practice is one of several Danish New Year customs, alongside watching the King’s New Year speech, jumping from a chair at midnight to “jump” into the new year, and eating festive foods such as kransekage.
Descriptions vary by region and family, and the plate-smashing tradition is less universal than televised countdowns or midnight celebrations. It should not be confused with the Spanish grape ritual or with the use of champagne glasses in other countries. The answer is plates because the tradition specifically centers on old or unused dishes broken at doorways.