[LOA--Paul]

Basically, 420 has become widespread code-speak for: "pot smoking," “time to smoke pot,” “let’s go smoke pot,” and “ain’t pot great?” Suddenly, the term was everywhere. There have been a host of speculative explanations about its origin: a police radio code for pot smoking in progress, the time of day Albert Hofmann first took LSD, etc. Many theories. This one website said It has actually been tracked to a code phrase used by a bunch of Northern California friends in the ‘70s who met every day around 4:20 p.m. to smoke out. They shared 420 with college buddies later, but how it spread beyond that is the stuff of legend. Somehow it got into the lexicon off those who followed the Grateful Dead from concert to concert, and 420 went worldwide from there.