Copenhagen's New Year's Eve tradition of throwing old plates at friends' doors is called plate smashing.
In Denmark, some people traditionally save unwanted plates and dishes, then break or throw them against the doors of friends and neighbors around New Year's Eve. Finding a pile of broken crockery outside a home is meant as a sign that the household has many friends and well-wishers.
The custom is a form of symbolic destruction at the transition between years. It is associated with friendship and good fortune rather than hostility, even though the action would normally seem aggressive or impolite. Modern celebrations may use the tradition less frequently than older accounts suggest.
The practice is often mentioned alongside other Danish New Year's customs, including standing on chairs and jumping into the new year at midnight. It should not be confused with the widespread practice of breaking a plate for entertainment at other times of year.