I'm going to wipe my feet on my neighbor's doormat.
Why do you want to do that?
I hate the old woman next door, and I'm going to release my anger on her innocent doormat.
While wiping your feet on your neighbor's doormat isn't really a big deal, it's still considered rude to leave your dirt on your neighbor's belongings. Whatever your neighbor has done to rouse your anger, acting in this way will only make the relationship worse.
Whatever.
I hope that you are willing to just move on, and not escalate things with your neighbor. You will always have to live next to one another, so it is best not to antagonize her, even with small things like this.