A java string: everyone should know
This is an example, how Java script can be used for bad works. I am giving an example, which is fun to do and show your friends. Its a primitive prototype only with no or little power to do any harm. The advanced one are dangerous. YOU WILL LEARN SCREEN-SHOTS SHOULD NOT BE RELIED UPON.
Its a three liner instruction.
You are reading this post, right?
1. Ok, Copy this string and paste it browser page's address bar.
Code:
javascript:document.body.contentEditable='true'; document.designMode='on'; void 0
2. Press enter.
3. Nothing happened? Click any text and hit backspace or start writing....try to delete this line

This one is dedicated to
FliGi7 
as I promised, this one is not a tutorial though.
Note: You can never save this "edited" webpage. Its doing everything on your local computer,thats too on the screen, not on the Server side or your cache (that is why, it is not a hack and I am posting here

).