[FreeTally]

believe it refers to the fact that there are some 420 compounds in marijuana smoke, but there are other theories.

Good grief, there are two predominate theories, and that aint one of them.

1) Its is alleged that in the 1960's, the police in California used a radio call signal of "420" to denote that they had viewed pot smokers, i.e., "This is car 54, we have a 420 in progress".

2) Something about 4:20 in the afternoon being the time you start smoking.

The "420 chemicals" think is nothing I have ever heard of, but the other two "theories" are widespread and accepted.

[StriperSniper]

1) Its is alleged that in the 1960's, the police in California used a radio call signal of "420" to denote that they had viewed pot smokers, i.e., "This is car 54, we have a 420 in progress".

That or something real close is the way I've heard it for almost 20 years.