How to edit/change each and every text/items in every webpage?

Have you ever tried to do this stuff...like changing text, images, links etc from the well known websites??? Can you do this?? Of course I can help you guys to make this happen. But what you can't do is save that webpage after modifying it.

Ok, let's start the trick. See the original Facebook page of mine.....and then the edited one...

                                                                            Original

                                                                             Edited 

1. Go to any website

2. Paste the below code in the address bar of your browser

Code:

javascript:document.body.contentEditable='true'; document.designMode='on'; void 0

3. You can edit the website , but you cannot save it