It is believed that the idea of celebrating such a day originated on Internet forums, where it was also proposed to choose Amsterdam as the main venue for this event. For the first time, Sex Day was included in the international holiday calendar in 2007 at the initiative of UNESCO, however, the holiday is not considered official. You can mark it as you like, but preferably several times a day, if you understand what it is about.
By the way, doctors believe that people who regularly have sex live much longer than those who do not, and get sick less. After all, sex strengthens the cardiovascular system, increases immunity, relieves depression, and also — promotes weight loss and improves the condition of the skin. So celebrate for health!