The Danish New Year's Eve tradition of smashing old plates against friends' doors is called plate smashing.
People traditionally save unwanted dishes and break them outside the homes of friends or neighbors. The custom is associated with friendship and good luck: a larger pile of broken crockery can signal that a household has many people who care about it.
Modern versions vary widely. Some people no longer practice the custom because of noise, cleanup, safety, or apartment living, while others use disposable or specially collected items. It is one of several Danish New Year's customs, alongside midnight celebrations and the tradition of jumping from a chair or sofa into the new year.
The practice is not the same as breaking a glass for a wedding or throwing plates in a restaurant as entertainment. Its defining setting is the home doorway of friends or acquaintances on New Year's Eve.