American Halloween (6:38)
Horrors of Halloween; Vimeo

So... a man is giving out candy on Halloween, and reads a spooky incantation while doing so. Then three adult trick-or-treaters show up, and come into his house. He thinks they're there to rob him, and he's willing to give them whatever they want, but they don't speak. Eventually he comes to think (as I had suspected from the start) that he unwittingly summoned some kind of demons or something. But the end is a fairly amusing (if ridiculous) plot twist.