OH MY GOD. Do they have a nice, green, lawn? buy a bunch of motor oil and pour it out on the lawn. But you got to pour it out in letters, and spell out "CUNTS LIVE HERE" or something like that.

Or you can Freeze up a bunch of cans of shaving cream, pull the tops off, and put the still frozen cans in their car. When it thaws it will be all over the place.