If you're talking about a hatchling, which do tend to nip when frightened, then the best way to "get used to being bitten" is to rub your finger quickly but lightly over a piece of velcro. 'Cause that's what it feels like.
Corn snakes usually aren't real agressive once they get used to you. You gotta remember that biting is really a snake's last-defense weapon. In the wild, biting something (even food items!) always runs a risk of ripping out teeth, splitting delicate mouth tissues, or even breaking a snake's fragile jaws. And snakes with mouth injuries in the wild are usually as good as dead.
That being said, you'll probably get bitten if you've just rubbed your fingers all over a mouse, and your snake is hungry. So don't rub your fingers all over mice. If you're feeding frozen/thawed mice, sometimes the snakes don't actually "strike" anyway -- they kind of nuzzle the mouse and work their jaws over it. So if you feel a tickle and look down to find that your overly-optimistic serpent is becoming inappropriately attached to your thumb, I'd suggest moving said digit.
If you have a larger snake, and the snake is hungry, and you rub mouse all over your fingers, and you wave those fingers in front of your snake, you'll probably get bit. It might even draw a tiny bit of blood. Even if you were "trying to get bit," and are ready for it, you'll probably jerk back. Your snake will probably lose teeth. And what if you don't jerk, and your snake decides it really is lunch time? You'll have to pry him off your finger, likely costing your snake a tooth or two. All of which probably could have been prevented by not rubbing mouse all over your fingers.
I really just don't think its worth it.
Thanks, and best of luck,
TS
*****
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