What do you think of my plan to spray my neighbor's lawn with bleach?
That sounds really cruel. Why would you spray bleach on their lawn?
I want to get back them.
Even if they did something to upset you, it's wrong to spray your neighbor's property with chemicals. You will destroy their lawn and could potentially cause them medical issues if they inhale the fumes.
I'm not scared and they deserve it.
If you are that upset with your neighbor, then you should talk to them. Getting revenge on them will just make them upset and will make your relationship even worse. Talk to them and explain why you're upset so that you two can hopefully have a more cordial relationship.