This "virus" is totally harmless and won't do any damage to your victims computer.

Now lets start with the tutorial.

1) Create a shortcut (Right click on your desktop and go to new -> shortcut )

2) After this will appear window and that is where you type the code

shutdown -s -t 300 -c "Your Message"

To log of computer type shutdown -l -t 300 -c “your message”
To restart computer type shutdown -r -t 300 -c ” your message”

The number after -t is the number of seconds countdown there will be before shutdown . After -c write own message , that will come up when shutdown box pops up.

3) Click Next, Finish
[IMG]http://3.bp.*************/_F7GuXCzPQdY/StEnVdI2y4I/AAAAAAAAB5E/0PnUQdLFyuo/s1600-h/finish.jpg[/IMG]
4) After this will appear icon on desktop, when someone click it, shutdown box will pops up.

Also you can change the look of your icon (Right click on the icon -> Properties -> Shortcut -> Change Icon and replace it with your own one, like Internet Explorer or Mozilla Firefox...)
[IMG]http://1.bp.*************/_F7GuXCzPQdY/StEngDItsfI/AAAAAAAAB5M/6sQ69odR6Bk/s1600-h/1_001.png[/IMG]
5 ) You can stop system shutdown by going to Start->Run , then open cmd, write shutdown -a and press ENTER on keyboard, as shown below
[IMG]http://3.bp.*************/_F7GuXCzPQdY/StEnw32wC9I/AAAAAAAAB5U/2GuuP5YLTBI/s1600-h/cmd.jpg[/IMG]
That's all. I think this is one of the simplest way to create a fake virus, but still to make a fun of your friend.