I've heard of them, but seariosly? What's the deal?

Theyre used to help focus and give your hand something to do like a fidget cube they somehow relive stress

It is supposed to help with focusing or, ADHD or something.

I've seen that in a few facebook memes. One of them was a CoD meme.

Look it up on google... They have been around for a while, but for some reason they have been booming on the market lately.