If you really want to wreak havoc with your mortal enemies’ psyches, pump their house full of rabid fruit flies that have no identifiable nesting ground or food source.
The flies will billow in clouds around their heads driving them to:
-flail their arms around spasmodically
-clap loudly at random times
-scream at invisible flying specs of annoyance
-repeatedly peek into bowls of apple cider vinegar laced with dish soap and cackle with self-satisfaction
-LOSE THEIR MINDS!!!!!