Get a nail-file.
Ignore the fact that you may come off as a nacy boy. Get a macho print or something if that makes you feel better.
When you catch yourself biting your fingernails, file them evenly instead. Do this in combo with the icky flavoured stuff, or if you're a female use dark-colored nailpolish that immediately will show if you're mistreating your fingernails - to get you more keen on not doing it.