It depends on whether or not you want to let him do that for you.
Your body is your own, thus you decide who touches you and how - or if they touch you at all. Some people wouldn't have a problem with this and to some people this is intimate or arousing, but that doesn't mean that you should agree to it and you shouldn't agree to it just to keep him happy either.
You ask him to put your tampon in for you - if he says yes then great, if he says no then it's no. It's no more complicated than that, if he questions it then explain your fetish to him so he understands. If this isn't a fetish, you actually need help because of disability, then explain that to him too.
say "here!" , open your legs and smile. I demonstrated for him first and now he likes to do it for me.
You say no!
It wouldn't hurt the baby, but why would you put in a tampon, if you're pregnant you don't have your period.
I hope you are not wearing a tampon when not on a period. This is unhealthy and if you are just starting your period you should not be using a tampon until you are older. The tampon box gives written as well as a diagram of how to put in a tampon. Follow the directions and read the warnings. This is very important.
Every tampon box has detailed instructions with picture of how to put a tampon in. Very gingerly Follow the instructions in the pack.
is there a special way to put a tampon in my anus
You might be uncomfortable, and the tampon would not be able to expand and function normally.
Put a tampon in or use a pad.
Put a tampon in your but
You can only use a tampon if you're menstruating - if you're a boy you may menstruate, but only if you have a uterus and vagina (e.g. if you're a trans boy). If you're a cis boy then there's absolutely no reason for you to be using tampons and nowhere for you to put a tampon as you don't have a vagina. So in short, if you are a boy you do not put a tampon in at all.
This is not recommended, it could get stuck.
Just put a tampon in. The water won't affect it.
you should put in a tampon and wear a pad in your underwear
She's the Man.