In the early 1970s a small group of hippie stoners at San Rafael High School in northern California used to meet at a designated location every day to smoke pot at 4:20 p.m. They did this so regularly that among members of the group "420" became a general euphemism for lighting up. The catchphrase spread beyond their immediate circle, beyond the high school they attended, and ultimately beyond California, so that within a decade or two pot smokers were using it across the country and indeed the world over.
That's the gist of it, but I've heard alternate stories before. Someone even tracked down a few of the people who claimed to be from that group.....
You can't school the already schooled. I'm pretty sure any weed smoker who does the whole "420!" thing knows the myriad stories behind it. Personally, I don't care for the 420 fad.
OP people are acting weird on grasscity today. Best to just log off and try again tomorrow. The earth is off it's axis.