I would wait her/ him to come to me and say sorry because I didn't do anything bad to him/ her.
I would say sorry first to her/ him even though she started it first because nobodys perfect
I would get it nicely to her and tell her that she needs to ask permission next time
I would get it and run away
I would tell her that I would do my assignment first then chat with her later
I would go offline without saying something