• Login as a user.
• Delete the user while still logged in
• Run command

You should get a message “you don’t exist, go away”

Not sure if that one is still around but I know one person who ran a script with “deluser $USER” and it ate root resulting in fun messages like that

the famous “This incident will be reported” error was briefly removed last year before being replaced with a less ominous version.

People would read the second message, type the yes prompt, break their system. But still claim that it was linux’s fault, and that the OS doesn’t work.