Pop up over site for Like and Share, How is it done?

JavaScript
1

I came across this website and I would like to use it for my own but I have no idea how they did it. I checked out the source code but I dont see anywhere I can change the url to mine.

I have looked everywhere and I cannot find the code. Does anyone know how they did this?

Site is

http://xbl4free.net/xbox/
2

Their content_script.js file has the code that achieves that.

I disagree though with the techniques that they are using. My first instinct is to close the page that attempts the coercion on there, and to never go back.