code for cannabis and things related to this. At 4:20 PM is the time when cannabis smokers are said to smoke the first joint after a successful working day. This is believed to be the origin behind the term, but no one knows exactly where, how and who coined the term in its time. 4/20 (April 20) has also become an international day of celebration for cannabis enthusiasts. Also in Denmark various events are held around the country the biggest being the annual Cannabismarch from Christiania in Copenhagen.