i just cheaked urban dictionary and they have a few deffs most of them have allready been talked about. Urban Dictionary: 420

being from canada though i especialy liked the one about the highway

:: Highway 420 ::
In Ontario, Canada in the 60's, marijuana grew freely on one of the Highways. This highway was later renamed in 1972 as Highway 420.

i'm gonna have to go find that highway and jack a sign now to bad i have noidea were it is...