What's so special about 4/20? It has long been debated as to why April 20, the unofficial holiday of the Marijuana enthusiast, has been celebrated. While there is one technically true meaning behind the day (and thus the number '420') there are a number of other things speculated to contain the holiday's origin. From Hitler's birthday to an imaginary tea time, there are a number of highly creative theories as to why stoners covet today's date. See our 10 favorite below, and check slide #11 for a real explanation.