You can play this prank on your friend computer disable his shutdon option.Its very easy you have to use registry trick and tips.
You can use a Registry hack to disable the normal Shut Down. Run the Registry Editor and go to
Create a new DWORD value named NoClose with a data value of 1.
Exit the Registry and reboot in order for the change to take effect.
You won't be able to shut down Windows in the normal manner from now on; you'll have to run Task Manager by pressing Ctrl-Alt-Delete or right-clicking on the Toolbar, choosing Task Manager, and then using the Task Manager's Shut Down menu to close Windows. If you want to reenable normal shutdowns, delete the NoClose value.