Keeping the fancy sudo warning forever
Create a file inside /etc/sudoers.d/ You can use this command
sudo nano /etc/sudoers.d/privacy
Now paste this line into the file.
Defaults lecture = always
Now close Terminal/Konsole, Reopen it and try to do something with sudo.
To re-set an account to see the warning once more, delete the sudo records for that user.
root> rm /var/lib/sudo/<username>/*
root> rmdir /var/lib/sudo/<username>
To add to +Michael JAMES his statement, locations might vary. On Fedora,
rpm -ql sudo
Shows a directory called:
/var/db/sudo
In this directory i found another directory called 'lectured' followed by my name. Removing my name from this directory show the warning again.
Edit: This is a one time solution to reset showing the message. You could of course use crontab to empty the directory so that the message is printed on a more regular basis.