Though I am VERY familiar with the activity, I have never heard of the 420 reference.
Could just be something in your neck of the woods or a generational thing.
Enjoy

Seriously? Do you live in the US? It blows my mind to think that people who grew up in this country would never have heard the whole 4:20 thing (it's actually a time of day/activity).. especially if you smoke.
I always assumed it would be known in european countries too though.
My neck of the woods spans almost the whole US to be honest. I've lived in Massachusettes, Texas, California, Maryland, Colorado and Florida.
So weird.. now I'm all paranoid haha
Never heard of it in California. Granted, I probably have a "sheltered" group of friends and I have never smoked anything in my life.