There's this girl who might ask me out and I want to reject her as revenge.
Why are you choosing to get revenge on her?
Because I want her to feel heartbroken.
You shouldn't make someone feel rejected by you just to get revenge. You will end up regreting this in the future if you realize you actually like her. However, she may never forgive how you made her feel.
I already have my revenge planned, I'm going to be vulgar to her as much as I can, and I don't give a fuck about what happens next.
You know if you go through with this then you'll be just as bad as she is, right? You should take care of your own life and make it as good as possible without trying to ruin others.