An evil cursed penny, the eponymous bad penny of the title, in order to murder people, would put itself on the sidewalk somewhere, heads up, and someone would see it and pick it up, assuming it would bring them good luck. But, rather than good luck, the penny would bring them a horrific and violent, gory death (!). And then, the bad penny would place itself heads up again right next to the mangled corpse of its victim, and whoever found the body would call the police, and after getting over the initial shock, they would notice the penny, assume it to be lucky, and pick it up; and then they too will die a horrible death (!!). So basically, it would essentially lift the plot from that horror movie The Grudge, but with a cursed penny, rather than a hateful, vengeful spirit of a murdered person (or persons); and whoever then encountered the cursed person/penny would then be afflicted by the curse, and so on and so forth, until everyone is dead (!!!). (Except for they must pick up the penny to get cursed. But they all will, since it's a horror movie, so they all die horribly. Mwa ha ha!) Oh, the humanity! (An alternate version of this movie could avoid simply stealing the plot of being an "homage" to The Grudge by having the penny purposefully place itself where it knows it will be seen and picked up, but positioned in such a hazardous place where the person who tries to pick it up will ultimately die in a freak accident for doing so.)
And then it will come out that the murderous penny is doing this in revenge for the plot to "do away" with them (pennies, that is), and the penny is simply acting in self-defense, fighting for not only its own life, but also protecting the lives of all its defenseless penny brethren. So who's the real villain of this piece after all? (Ooh! A twist!) A scathing social commentary on the hypocrisy and thoughtless depraved genocide mankind perpetrates on all kinds of material wares! Oh, the coinage! And this subtext will really give you something to think about that will make your thoughts worth even more than a penny (which is appropriate, seeing as how movies cost $12.00 nowadays). And of course, this will be one more addition to the illustrious line of classic movies that push the "blame humanity first" agenda that's all the rage nowadays, exposing as it does man's inhumanity to currency!
Here's the sadistic story of senseless cents slaughter: