That's actually how I would confront jerks and bullying. If you can intimidate and scare the person, then you've already won.
As for mental instability, I'm of the psychological kind.
I used to have very scary and disturbing hallucinations, NSFW kinds of things, but thankfully, they almost never appear anymore. Now it's just nightmares, but those are uncommon.:p
What kind of bad stuff happens to you? (You don't really have to say if you don't want to.)
