420 (cannabis Culture)
420, 4:20, or 4/20 (pronounced four-twenty) is a term used primarily in North America and the United Kingdom to refer to the consumption of cannabis and, by extension, a way to identify oneself with cannabis subculture. Observances based on the number include the time (4:20 p.m.) as well as the date (April 20).
Read more about 420 (cannabis Culture): Origins, April 20 Observances