Take a box full of cows
add a few calves
and a few foals
then scatter them randomly across the living room floor
and turn off the lights.
Oh, and if you have one handy, add in a dragon for good measure.
This is a sure way to keep criminals out of your house.
Or at the very least it will leave them writhing on the floor in pain from stepping on unknown objects in the dark.
Cheaper than ADT.
When walking through the house in the dark I perform a step I like to call the Midnight Toy Shuffle.
Pain is a good instructor. I've stepped on one too many toys in the dark.