The Easy / Take It Nice Command can ensure that you still have some fingers left when giving your dog a treat or a toy.  Eager dogs can sometimes forget that there are human fingers behind what they want, so the The Easy / Take It Nice Command is something that every dog should learn.

1.  With your dog sitting in front of you, offer him a treat     and firmly, but not angrily, say either "Easy," "Nice," or "Take It Nice." 
2.    If your dog tries to grab the treat, pull your hand out of reach, and then offer it again.  After a few tries, your dog should realize that he has to move more carefully if he is going to get what he wants.  When he gently reaches for the treat, hand it over and praise him.
 
 
NOTE:  The choice of command is yours but as with any dog training, be consistent.  Use a word command that comes naturally to you because using several different commands for the same thing will only confuse your dog.  Remember, set him up for success.

Disclaimer
Please consult the services of a Professional Dog Trainer, Behaviorist or Veterinarian before implementing any of the advice contained on this site.