An incredibly idiotic holiday, usually celebrated by wanna-be potheads who think that he/she is cool.
However, some people just smoke during 420 because, hey, they want to get high.
So chances are, if you're celebrating that stupid holiday...you're pathetic. (unless you're the noted above)
I smoke whenever, because weed is great; anytime of anyday.
boy: "it's 420! i'm getting sooooo high!!!
me: "go lick a window, you stupid, poser, asshole."