420 (cannabis culture). From Wikipedia, the free encyclopedia. 420, 4:20, or 4/20 (pronounced four-twenty) is a code-term that refers to the consumption of cannabis and by extension, as a way to identify oneself with cannabis subculture or simply cannabis itself.20 event in Golden Gate Park, San Francisco, April 20, 2013. Students and others gather for a 420 Day event in Porter Meadow at the University of California, Santa Cruz, campus on April 20, 2007.