Of course this is a joke... but its not.

A group over on 4chan (you can look it up) decided it would be funny to troll the far left by making an innocuous hand gesture into a hate symbol.

So, they spread this "rumor" that the ok symbol really meant white power.
And the left ate it up.

This hand gesture, held upside down on the leg has another meaning about a punching game.

I don't see any possible way a "thumbs up" can be seen as offensive!

Well, you are wrong.

As you can see with the ok symbol.
Oh, by the way, to you use # (hash tags)? Or the symbol for Hail Hitler?

This is why political correctness is so bad. Taking a part of language and saying it is now off limits. There is no way you can avoid offending anyone. And you will tie yourself in knots trying.