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

• 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

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.