Edit the file /etc/sudoers
and find the line:
Defaults env_reset
Now add ,insults
to the end of the line so that it reads like that:
Defaults env_reset,insults
From now on, sudo will insult anyone who mistypes his password. See for yourself:
[sudo] password for foo:
Hold it up to the light — not a brain in sight!
[sudo] password for foo:
Speak English you fool — there are no subtitles in this scene.
[sudo] password for foo:
I think … err … I think … I think I’ll go home
sudo: 3 incorrect password attempts