Sounds like it's time to sharpen the teeth and claws to go on a biting and clawing spree! (If only, right?)

In an online situation, the best thing to do is just ignore them, maybe report them to staff, and then try your best not to let it bother you. Easier said than done though, I know... I've had my fair share of nasty people replying to me on other forums too. It will only make it worse for both you and the other people if you engage with them beyond an "I don't like that, please stop" sort of comment.

In an IRL situation, similar can be said, but there's no "reporting to staff" in many of those cases (unless it's like a work or professional thing, then you could report them to superiors). Otherwise, all you can really do is ignore or try to calmly ask that the person not speak to you in that manner (or at all if that's what you wish) and again try your best to not let it bother you.