Black Day is an unofficial holiday observed on April 14 each year. It is mostly observed in South Korea by singles.

The day is associated with Valentine's Day and White Day as a holiday on the 14th day of the month. On this day, people who did not receive gifts on the previous two days gather and eat jajangmyeon. This day is specifically for single people.

Black Day builds on the romantic aspect of Valentine's Day and White Day. As the chocolates received on Valentine's Day are interpreted to symbolize a man's popularity and the chocolates given on White Day are used solely for romantic purposes, Black Day focuses on the people, especially singles, who did not receive any gifts on either of the holidays.

On the day, singles who have not received presents on both days gather wearing black to 'commiserate' over black-colored food, especially jajangmyeon. During the meal, they complain about their lack of intimate relationships and chocolate gifts.