Black Day (South Korea)

Black Day (Korean: 블랙데이) 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, noodles with black sauce. This day is specifically for single people.
Origins.
In South Korea, Valentine's Day and White Day are both celebrated as occasions to give gifts to significant others. Valentine's Day is celebrated on February 14, when women buy men gifts (usually chocolate). White Day is celebrated on March 14, when men reciprocate the gifts with their own, also present in the form of chocolate. As both occasions fall on the 14th, other holidays were created by the government of South Korea for all other months to continue this trend. The creation has also been attributed to marketers.
Meaning.
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.
Impact.
This day is targeted by businesses, who hold various events and advertise their products, a strategy known as 'day marketing.' The events are highly popular, and include matchmaking events such as speed dating, jajangmyeon-eating contests, and discounts on items.