Would it be wrong to key my neighbor's car because he won't park properly?
Do you think that would make him park correctly?
I don't know, but it would make me feel better.
I'm sure it's frustrating having to deal with a neighbor parking their car in the lot wrong, but threatening someone's property is never a solution. Doing so will only make your neighbor scared and angry at you. They are also likely to call the police on you.
I'm not scared of that.
Even if you aren't scared, damaging your neighbor's car is still wrong. If you have an issue with the way he parks, you should talk to him about it, instead of threating to key his car.