People smoke pot on 4/20. Really, they smoke it every day. It's just especially prevalent on the 20th of April, thanks to an old ritual founded on the concept of stickin' it to The Man.
Stoner Christmas happened to fall on a Saturday this year. In Philly (and a whole slew of other cities around the world), the day was marked by a crowd of people gathering to toke up together at—you guessed it—4:20 p.m. Philly's "celebration" took place on Independence Mall near the Liberty Bell. There was a police presence, but the officers kind of just let the whole thing play out while making sure no one got hurt or participated in serious crime.
Surely, in a city that saw 331 murders last year, most people understand that the bulk of the police force had more important things to do than haul scores of folks down to jail for petty pot crimes. THIS GUY IS NOT ONE OF THOSE PEOPLE.
A video of Philly's 4/20 event popped up on Reddit and has started to make the subsequent rounds on the Internet. It shows one incredibly concerned citizen repeatedly yelling to the authorities in the area to make sure that they're aware that people are inhaling marijuana in their immediate vicinity (!!!!).