Hey guys, I don't know how to explain this, but I'll try

For example

>Person 1: *says something*
>Person 2: That's sexist
>Person 1: That wasn't sexist
>Person 2: Yeah it was
>Person 1: How was that sexist?

It doesn't have to be sexism, that was just an example. You could replace sexism with racism.

Is this some sort of fallacy? Or is this what we call a lateral attack or something?

I hope you guys understand what I'm asking.