While running a "summer slasher flick" one-off adventure for d20 Modern, I wanted to make sure that the characters still acted like the idiots we normally see in horror films--particularly since all my players were horror fans, and certainly knew better. Below is the mechanic I settled on. It added a sense of plausibility to the genre, and the players loved it.
Since the trope ultimately has its origins in gothic literature, the Foolishness Check would also be appropriate in a gothic fantasy setting/story. It may now, however, be used as frequently as in a modern horror game with victim-style characters. Since that slasher game, I have kept the mechanic in my back pocket to use whenever I feel the need.
