Both Parents are afraid of my pet snake and they refuse to step anywhere near it. How can I help them not be so afraid?

Does either one of your parents actually want to get over their fear of snakes?  Or do they enjoy it?  If they don't want to, there is nothing you can do but enjoy their fear along with them.  "Uh Oh, she's hissing again!!!  Why does she only hiss when YOU are here?"

  "She's gonna JUMP right through the glass!"

If they do want to, first have them read up on ball pythons, their habits as pets, and their morphs.  Then ask them to watch some videos of people handling ball pythons.  Or if they are too up-to-date to do any reading, just start with the videos on YouTube.  Then let them watch her from across the room.  "LOOK, she's curled up in the corner!"  "Why doesn't she move?"  

Maybe eventually they can touch the snake's tale.  "Whoa!  It's DRY!"  "It's warm?  I thought snakes were cold and wet?"

If they would just hold her they would see how sweet she is.  I've been a snake mom 3 times over the years.  They really are very clean and loveable pets.  If you handle them a lot, they will become somewhat affectionate.  People are SO ignorant when it comes to reptiles.  They judge them without knowing anything about them or even being near them they form their thinking about reptiles based on what they are TOLD to think by others.  Your parents are really missing out by not getting to know their little grandsnake.  

Jim Is - that's not an intelligent thing to do about the second day after the snake has eaten.  Snake **** is like tar and not easy to clean up.

Just be happy that they allow you to keep something that they are scared of.  You cannot make anyone like snakes but you can help them stop fearing snakes by reassuring them that your snakes are not venomous. 

sneak it in their bed at night

This would be better asked in a psychology category.  There are several ways that people can work on their phobias, between small steps over time to conquer the fear and full on submersion all at once. 

Why do your parents have to stop being afraid?   

You are now an adult.  Your parents no longer have to cater to you.   They are afraid of snakes.    Be a good host and put the thing away when they come over.

I don't expect my guests to be around my dog if they don't want to.   She has a bed in my office and can be very easily put away.

?????

Nothing. They don't like your snake, so why force them to like it? They accept you and your love of snakes, so leave it at that. Imagine if you were terrified of dogs, and your parents kept trying to force you to pet one. Not cool, right? My own mother cannot stand snakes, or rats, or bugs, but hell, she let us kids have them all growing up. She plucked up the courage to touch one of my rats one time and was surprised at how soft she was, but that didn't make her a rat-lover. She just wanted to make her kids happy.

So stop it. Just leave it alone. Stop trying to make your parents "love" your snake(s), because they won't, ever. Just accept that as they accept your love of them.

Nothing.   They have a preconceived notion.  Just leave her in her viv when they visit.   She's just as content to be left alone anyways.

Not a thing, I'm with your parents on this one. Many, like myself, have a deep seeded fear of snakes, harmless or not. Walking across the yard and suddenly the ground starts moving, usually pretty close to my foot. Scares the crap out of me and has gotten worse with age.  There is not one thing that can, or should be done. Keep it in it's tank when your parents are over, just like I had to lock my dog in a room when certain people visit.

Well you know what they say about facing your fears....

Is their dear rational? If it is then you can negate it somewhat. Getting them to gentle stroke it while you hold it, to show they aren't slimy, for example. Learning it's behaviour, it's mood, just being comfortable nearer it. 

If their fear is irrational and more of a phobia, it may not be very straightforward.