
This is not just a guy's nature, it just means he is shitty. I find offensive slurs not okay to use and many of my friends aren't okay with others using it or using themselves either. If he continues despite you asking him to stop too, that's also not great because he should be respecting that and ADHD isn't an excuse either because it's not an excuse for being offensive to others
2/2 ...OP, if this bothers you, please talk with your partner about this, this needs to become an open discussion. It doesn't matter if they're directed towards anyone, he needs to respect what makes you uncomfortable, despite whatever "habits" he might have. If he can't do that, then that's just one sign of a larger problem here.