Steps to Show a error message and shut down friends computer
msg * I don't like you
shutdown -c "Error! You are too stupid!" -s
2. You can change the message by replacing the text by your message. Save it as abc.bat.
3. After saving just double click on the file to execute the file. You can also send the file to your friends and ask them to open it.
4. Done..!! This will show an error message and Shutdown you friends computer