Age Protect?

Is there any plugins out there that could age protect an image? I know of several websites that have something like this but I have no clue what they are using.

So pretty much what I want is an image to be blurred out then when the user clicks the image for the full non-blurred out image the user is then asked ‘Are You Sure’ or something along those lines to view the picture.

There has to be something out there.