It was just 4:20

[Hand of Man]

What the fuck is 4:20?

This was a stumper for me as well a few years ago...
The younger guys at work all seemed to know that 4:20 is when you
spark up in preparation for the end of the working day (I think), but
a time when fellow stoners strive to share a community buzz. None of
the veteran tokers seemed to be familiar with it, so it must be of only
a couple of years' derivation...From a movie?? A particular comic??
Anyone???