At times we have to work together, there is a fair amount of brainstorming and coding involved. They have a habit of swearing(real bad words in native language) on the work they do. Although I have been tolerating it for quite a while things are going out of control now. Just the other day when I spoke up with a suggestion (which they disagreed), I was immediately snapped at and called an idiot, I still tried to press on that but things went to a yell. I stayed calm though.

Also this is turing into mockery (I am not fully sure about their intention though), today, we had coded a bug fix and there was some error left, I immediately told them to make the changes at A and B. One of our colleagues was standing nearby and they make a laugh at me saying, go ahead and ask me to change everything, next I can do your personal errands.

They either did that to show off to that colleague that they do all the work or to insult me, I am not very sure as it confused me.

The question really is, how to ask them to stop all this without being rude about it?