The Danish New Year's Eve ritual involving broken crockery is called plate smashing.
In the custom, people throw old plates and glasses at the doors of friends or neighbors. A large pile of fragments outside a home is traditionally interpreted as evidence that the household has many friends and well-wishers.
The practice uses unwanted or old tableware rather than valuable household objects. It is part of a broader Danish New Year's tradition that also includes watching the monarch's annual speech, eating festive food, and jumping from a chair at midnight to symbolically leap into the new year.
Descriptions of the custom vary by region and family, and it is less universal than televised celebrations or midnight toasts. It is also distinct from simply breaking a glass for luck: the Danish version specifically emphasizes leaving crockery at another person's door.