Oh hell NO; I don't go to such sites and wouldn't even know how to find any. LOL"
==
One of my bros was looking at some porn when his browser locked up and he got a message like this.
It freaked him out, he shut down his PC cold (the warning covered his screen so he had to unplug the PC) and cleaned out his browser history when he restarted the PC.
When he told me about it, I explained it was just a javascript "trick" that locked the browser. And I noted the FBI has done some unsavory things, but they're not into ransom-ware extortion - the warning was obviously a fake.
Had it been a real ransom-ware attack, it wouldn't be just his browser screen that was locked - it would be every file/program on his computer. What he got was just a simple-script that actually scares and fools a lot of people into sending money.
In the case he ran into, just cleaning out his browser got rid of the "FBI extortion warning". But it could just as easily been a real ransom-ware that encrypted the files on his PC and he'd have had to either pay the ransom or re-format his disk and reinstall Windows. (and of course, lose all the files he did have). I hope it makes him think twice from now on before visiting any untoward websites or clicking on a blind link!