Ghosts

Last year, when they were still children, they went trick-or-treating. You followed them, in case there was trouble. Next year, when they're teenagers, there could be problems – spiking the punch, necking in the corners, smoking illegal substances in the bathroom... You remember that sort of thing, don't you? Of course you do. So, this year, on a holiday that gets wilder every year, let's keep the fun under control. We'll have a Halloween party. They'll love it.
But what if guests show up who aren't on the guest list?