This is just a small rant

I was in a trading server today just minding my own business, looking for offers for my cow. This random girl trades me and starts adding random low tier legendaries, I said no thanks halfway through but she disregarded what I said until I finally said something so incredibly offensive to her. I said "Bro stop adding". She starts to say that she would report me for calling her "bro" as it's not her gender. Is it really that big of a deal to call someone bro? I've never really had this issue.