I'm going to make fun of a transgender girl who's been harassing me
Does she really deserve all this?
I think she does. She is a harassing person who needs to be taught a lesson.
Instead of making fun of her, have you thought about just letting them know that they are hurting your feelings? Being harassed isn't fun, but making fun of them back may just make things worse overall for both of you.
If she listens to that then I can try it. But those types of people often are so full of themselves that they can't be bothered to talk things out.
You're right that some people just can't be reasoned with, but at least trying might be worth it. If it doesn't work out, then you could try just walking away and ignoring her harassment-- it's better than starting a feud with someone that may never end at that point.