I'm on Mac Safari, what IS that gray float-up box?

Looks like an ad spot, but it's just a blank box that I have to x out every other thread I open.

WTF is it supposed to be/do? It's driving me nuts. Somebody describe the ad.

I would use Firefox or Chrome and adblock plugin.

I hate switching browsers. It always entails bullshit like certain things not working right, etc.

Getting to that point though.

There it is again.

That means you're gay, veegoh.