Mail slots are your friend! Hoses, water balloons filled with urine, dog crap, and other things can be shot/slipped through in a jiffy!
Epoxy in any lock is always a great ratings grabber.
Collect (or make) containers that have "explosive", "chemical waste" or similar markings on 'em. Several of these next to the idiot's garbage can will alert the pick-up crews to a local lunatic.
Does he/she hate cats? Any trees around? Tie a large fish to an over-hanging tree limb, preferably under the bedroom window.
A few crickets inserted into a garage can drive anyone outa their mind.
Have a paint-ball gun? Suck the paint out with a syringe and replace it with Hershey squirts, chicken liquid, or any other choice of stinky/maddening liquids.
Place a classified add in the paper announcing "must move for new job! giant house-clearing sale!" along with the goober's address. Set it to begin around 6am on a Saturday, right when the poor snot is crawling outa bed.
Cans of insulation foam can wreak all kinds of havoc! Especially that tire-filler stuff.
Window-mounted AC units usually have a drain plate/pipe. Bubblegum can easily stop this up, and odds are the sorry putz won't even notice the over-flow.
Enjoy!
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Flakbait [Delta6]
Delta Six's Flight SchoolPut the P-61B in Aces High