what ive read a bunch of mexican hs kids, i guess called "waldos", decided to get high at 420 each day, everyone in the town eventually adopted the idea, and i guess the greatful dead were from the same town, so of course they pread the idea big time, and it just sort of took hold, but i know for a fact that its not the police code, ive seen many reports done by people that cant find any police codes for anything drug realated