So now instead of a "Welcome! Sleep in here!" sign, I have a "Please throw this rock at my window in order to vandalize/rob/rape/scare the shit out of me in the middle of the night!" sign. Seriously, they may as well have filled the planter with baseball bats, hatchets and lock picking kits.
Next time I am going to take all planter-filling responsibilities into my own hands. I'm thinking quicksand or king cobras might be nice.