It wasn't always, but 4chan trolls tried to make media outlets believe that it was a "white power" symbol (with the three fingers held up representing a "W" and the thumb-forefinger circle + wrist/arm representing a "P"). They succeeded a little too well, and so not only did media outlets report on it, but racist groups saw that reporting and went "dang, Cletus, we should start doin' that!"

So what started as a stupid joke has actually manifested itself.

This is the very first time I've heard of this. Just asked my wife who definitely pays more attention to current events and politics than I do and I just taught her something new. We're in America.