Amanda Holpuch in the New York Times in June 2023:

South Koreans became a year or two younger on Wednesday after a law standardizing the way the government counts age took effect. There are three common ways to count age in South Korea, but the government has changed its civil code to recognise one: starting from zero on a person’s date of birth and adding a year at each birthday. This is the age-counting method used most often around the world, but it is a departure from the country’s most popular method, often called “Korean age.” Under that system, a person is considered 1 year old at birth, and a year is added to their age each Jan. 1. This meant that an infant born on Dec. 31 was considered 2 years old the next day.

Every extra square metre I experience on this planet I find new and wild ways that humans have figured out how to exist. Korean Age isn’t the weirdest, but it’s up there.