The Origin of 4/20

Edit: I meant to post this on 4/20 at 4:20, but then I forgot.  Which is somehow appropriate.
Someone on the radio today was wondering if it had something to do with Hitler's birthday, since he was apparently an environmentalist. (Although I'm not sure how many environmental impact studies they did on the blitzkreig strategy, and in any case I'm not sure what environmentalism has to do with smoking pot.) Good news: it doesn't.

About 15 - 20 years ago, there were two high school students somewhere in Northern California or Oregon. They liked to get high every day after school. School got out at 4:20. They used the end of school as their code for what they'd do as soon as school ended. That way, they could talk about it right in front of teachers and no one would ever know. "Hey dude, we should 4:20 today." That's how it started.