Electing him over Hillary.

When you're mocking things that have nothing to do with their (reprehensible) views, like body-shaming.

Edit: I will say it is possible to make fun of things without going too far, but people often go too far.

When you go after their kids

Say what you want to them about anything except from their kids the kid hasn’t done anything it’s just a child so don’t involve it.

when you yourself say the same things you started mocking them in the first place for

The real answer is simply to not mock them at all. You just make yourself angry, and they probably wanted to provoke you.

Otherwise, you should probably stop if they’re begging for their life. Maybe actually a few hours before that.

As long as you are targeting their backwards worldview, and not them or anyone they care about, I guess it's fair game. People get really defensive though, so sometimes you're better off just asking people how they got there so you can watch them dig themselves into their own hole. Hopefully, they'll be introspective and try to self improve; plenty of people are capable of it. If somebody can't defend their worldview, but they don't feel attacked in the process, a lot of people can self correct, even if not as far as you'd like to go.

It doesn’t, they want to dish it out they need to be able to take it.