Requirements:
A WINDOWS Computer (most likely your friends :/)
A friend to prank
1.) Right click on your desktop and create a new shortcut
2.) In the box type C:\Windows\System32\shutdown.exe -r -t 10"Your Message Here"
-Replace the "Your Message Here" with what you want
3.) Once that is created, open up a file explorer and type in this "C:\Users\Administrator\AppData\Roaming\Micros oft\ Windows\Start Menu"
without the quotes, also replace the name "Administrator" with whatever your username is for windows
4.) Drop the shortcut right in there and drop it again in Programs, startup
5.) Your done, everytime there computer starts up, it will restart, and it will show your message.
To get rid of, F8 while booting, and boot in safe mode. Now delete the shutdown file in the startup