Order pizza and other food to their house and pick it up at their doorstep claiming that you don't have a phone.

Stand over the plants in your yard with a hose and Scream, "I have your life in my hands, bow down to me!". Then point at each one and declare them good or bad plants, while watering the bad ones.

Bring them restraining orders on inanimate objects in their house. (i.e., chairs, books, lamps, etc.)

Ask them if you can put your trash in their cans, if they ask why say, "Mine are full of bodies", then stutter and say, "I uh mean other garbage." Walk away laughing hysterically.

Patrol the perimeter of your yard while carrying a broom. If they come close state that there is a 3 foot neutral area between the two yards.

At night transplant the plants in their garden. In the morning say, "looks like they're on the move again."

When they're watching TV, pull a lawn chair behind their window. Sit down with popcorn and a drink and ask them if they could open a window so you can hear too.

Build snowmen with name tags of your neighbors. Each day hack off a different part of their body.

Use your TV remote to change the channels on their TV from outside. If asked why, say you protest such programs. (The more educational the program the better.)

Dig shallow graves at night filling your yard with brown grave patches. Make markers out of household appliances.