The official name for April 20th, the holiday for the celebration of Cannabis.
A day to be taken to do nothing but spend time with friends, and smoke, vape, eat, as much chronic as possible.
One particular tradition is to smoke blunts/joints all day long. You take the roach from each blunt/joint and mix it in with the chronic for each additional blunt/joint. This is known as a generation. The second blunt/joint with the first roach is a "second generation" blunt/joint. The number of generations a person reaches states how good of a chronica you had.
This holiday dates back to the days of ole. It predates any other holiday, religious or celebratory, in accordance that humans have been using and celebrating the use of chronic since the dawn of time.
"Have a nice Chronica!!!"
"I smoked a 20th generation blunt on Chronica this year!!!!"