A man lights up a marijuana joint at Golden Gate Park in San Francisco,  Tuesday, April 20, 2010.  Marijuana legalization advocates lit up across the country during the annual observance of 4/20, the celebration-cum-mass civil disobedience derived from "420" - insider shorthand for cannabis consumption. (AP Photo/Marcio Jose Sanchez)

WHY IS IT CALLED 4/20?

theGRIO REPORT - Every April 20th weed smokers all over the country 'observe' a sort of underground holiday of sorts, where marijuana is consumed on or around 4:20 pm -- and depending on the circumstances, for an entire day...