4:20 is the stoner's excuse to get high on pot. The story of how it began has many versions, all of which are plausible considering the stoned sources. I heard it had something to do with the time people got out of school and met in a vacant lot to light up. This ritual continues today all over the world where it's 4:20 eventually everywhere. In fact I have to stop this little bit of writing to light up. Happy 4/20, y'all. Love peace and good buds forever.