420 Meaning

Just as many other organizations or proponents of illegal (and sometimes even legal) actions, the people who coined the terminology may have used Adolf Hitlers birthday for a reason. The reasoning there is really an aside that since we dont actually want to celebrate his birthday, draw the focus to something else.

The 420 meaning is nothing more than the National Organization for the Reform for Marijuana Laws (NORML) making a one day push to promote legalization of marijuana. The University of Colorado even goes so far as to hold an unauthorized public smoking event..

Source: http://vernoncroy.com/420-meaning-legalizing-marijuana-420-meaning-2010/