Now the "Challenge" make them horrific! Scary,nasty.menacing! Deflate them then have a large air tank full with a large throat air valve and quickly inflate it when someone passes by!
If it goes "BANG!" it will be a very effective scare! (Be ready to video tape the "Bang!")
There. Feel better now?
If people park next to your property to see your displays quick-inflate it right beside their car,popping-up right next to them.
Distract people,then suprise-scare them,lull them, then "GOTCHA!!"
To insure they will react at least some how add some stink into their air supply.,all ready for if/when it bursts.