[deberon]

The visudo command is often times available as well. It won’t let you save a malformed sudoers file. Finding other footguns though is an exercise for the reader.

[hinkley]

It will however let you accidentally break "sudo su -" and happily tell you to go fuck yourself afterward.

[fragmede]

sudo -s or sudo -i

[hinkley]

That will not change sudo's attitude toward you once you've bungled the sudoers file.

[fragmede]

visudo

[hinkley]

No. Visudo will only stop you from making a malformed sudoers file not from deleting lines you don’t understand.