Here’s a devious little device about the size of a quarter that you can set to make several different eerie noises every few minutes. Choose from creaking, scratching, gasping, child’s laughter, and a whispered “Hey, can you hear me?” Or set it to randomly play any of these.
Use the attached magnet to secretly stow it away in a coworker’s cubicle or your brother’s bedroom. It’ll absolutely drive them crazy…