Naming a hog is very much a personal thing. It has to be a name that you like and is the sort of name you might remember.
In the past I have sometimes started with descriptive names for the hogs. For instance, years ago, I had a young one which was much smaller than all the others and so I used to call it midge. Of course it couldn’t stay midge for ever, because another midge might come along, so it eventually was changed to magic, which sounded very similar and I thought was a nice name.
Similarly I might initially call a hog pale skirt, dark face (or some other description) which is then shortened to psdf and then try to create a name from those letters. That way I am reminding myself of the identifying features in the name at the same time – although some may find that a bit too complicated!
Sometimes a hog might remind you of someone. I once had one who used to remind me of the (older) Queen Victoria. Although she wasn’t called Vicoria, but could have been.
If the hog always turns up at the same time, you could call it a number, or a number in another language.
You could call all the hogs which you first see in any given year, names starting with the same initial.
But you also need to consider whether you know if it is a male or female and if not sure pick a name which would do for either. But really it can be pretty much similar to how you would name any animal.
Good luck. I’m sure something will come to you, sometime and that will become the hog’s name.