Happy 4/20: Snapchat Takes Flak Over Bob Marley Filter And other marijuana-related headlines By Newser Editors, Newser Staff Posted Apr 20, 2016 11:13 AM CDT 7 comments Comments It's 'national weed day.' (AP Photo/Ted S. Warren, File) (Newser) – It is 4/20, as pot smokers everywhere—or the people who sell to them—are surely aware. Some related stories: Snapchat marked the day with a special Bob Marley filter for your selfies. The problem is that a loud chorus on social media is complaining that it amounts to "digital blackfacing." See Mashable. So why the association between 4/20 and pot? It's the time of the afternoon that a group of 1970s high school stoners would meet to partake, and the Grateful Dead played a role in popularizing it, explains a post at Digg. It has links to stories debunking other explanations. Vox rounds up other need-to-know factoids about "national weed day." Marketwatch takes a deeper look at how the day has gone mainstream. Think money. Indeed, a lot of of pot is being sold on 4/20, perhaps in record-setting amounts, reports Money. It's going to be a very big day in San Francisco, as KTVU explains. Canada might soon join the legalization club, reports the Huffington Post. USA Today offers a list of specially themed movies to watch.