She goes around setting fire to small businesses to remind them they need insurance. If they already have insurance, so much the better. That means she has just rewarded their prudence.
She takes the neighborhood pets to the pound and has them put to sleep whenever they wander into her yard. It's to remind her neighbors that they need to take better care of them. She tells the heartbroken children who come looking for them that it's better Mrs. Fluffy be in heaven than out on the road where she could get hurt, sick, and cause a car accident. After all, they didn't want Mrs. Fluffy to get hurt and suffer, did they?
She smiles kindly and offers them cookies once her lecture is done. When they inevitably reach out to take one, she slaps their hands and tells them not to take treats from strangers. She then threatens to call their parents and sends them home. They usually run down the pathway, crying. She'll shake her head at that and tell herself she ought to remind them not to run. It could be dangerous.
She checks books out of the library, not because she wants to read them, but because she doesn't want other people reading them. Harry Potter and Narnia, Chrestomanci and Artemis Fowl- all of which could corrupt the minds of children. Not their morals- she wasn't worried about that. But it gave them false hopes about other, better worlds. She couldn't bare the thought of millions of heartbroken children discovering that there was in fact no magic in the world. So she checked them out, renewing them for as long as the library would allow before turning them in, only to check them out again. Her living room is filled with children's books.
She watches her neighbors constantly. Sometimes with her binoculars, but usually with her naked eyes. Whenever something unsavory happens (and to her mind, most things are unsavory), she makes sure to write it down. It will be printed out the next day in her daily flyer and posted around the neighborhood, usually followed by an article about Standards These Days and how low they had fallen. The flyer is her passion. In it, she exposes the filthy underbelly of her little home town. In it, she gently reprimands her fallen fellow citizens, and then helpfully suggests some healthy alternatives to their individual shortcomings. If she keeps slipping an article on lung cancer in David Moreno's mail slot, maybe he'll stop smoking. If she keeps giving Dotty Worchester wedding magazines, maybe she'll finally make an honest woman of herself.
When she goes to the store, she takes her hat pin and pokes holes into the condoms. She believes that if you're going to have sex, you must deal with the consequences.
She hoses over children's chalk drawings. Sidewalk art is a precursor to graffiti.
She sleeps well at night, secure in the knowledge that, because of her, the world is a lightly more sensible place.
She is, in her mind, a good citizen.