2 Answers

Nerves, you like pain, self punishment for bad spelling? 

Try it this way: "Why am I always biting my fingers?" 

Or "Why am I biting my fingers all day?" 

Finger and nail biting may start out as a silly habit, but can actually turn into a serious problem both for the health of your fingers and nails and your social image. Finger biting is seen as a childish behavior and a sign of insecurity and shyness. This can be a problem for anyone in a business situation. Stopping takes a commitment to repeating these steps and remaining focused on the goal.

How to stop biting your fingers and or fingernails

Things You'll Need 
Band-aids
Nail polish remover
Nail clippers
Nail file
Gum

Instructions
1
Start by trying to figure out why you bite your nails. It could be stress, boredom, the need to have something in your mouth or a nervous habit. Focus on the problem first and make a conscience effort to stop yourself before you start. If you figure out it's due to nerves, then when you feel yourself starting to get nervous, just avoid your hands altogether--sit on them or place them behind your back, make your body do something else to deal with its feelings.

2
Clip your fingernails. Make sure you make straight, cleanclips and your nails are left with unsplit edges. Clip them down as short as you can. Use a nail file to further straighten and even out the edges.

3

Wrap a band-aid around the tip of each finger. When you go to bite your finger, you'll be biting a strange material and will not want to chew on those fingertips. Wear these as long as you need to stop.

4
Get out a bottle of nail polish remover. Fill the cap with polish remover. Dip each finger into the polish remover. Let your fingers air dry so the liquid soaks into your skin so the scent and taste will last longer. Every time you go to bite your fingers, you'll get the sickening aroma and then a disgusting bitter taste that will make you want to find something else to chew on.

5
When you get that feeling that you figured sets you into this state of finger biting, instead of having to resist the temptation, simply replace it. Chew on a piece of gum when the feeling strikes you (nervousness, boredom, etc.). The chewing of the gum will keep your mouth busy and spare your fingers.

Read more: http://www.ehow.com/how_4530195_stop-finger-biting.html#ixzz2mb2xJo3d

Because they're easier to reach than your toes?