You can drive someone crazy by removing the little pizo-electric speaker and chip assembly from a singing greeting card and hiding it somewhere inside a co-workers desk. The cavities in the desk make it almost impossible to locate. It will take about two hours before the victim is ripping his/her desk apart to find the little ba$tard before they have to listen to "Jingle Bells" one more time. Its sort of like the chinese water torture, very funny to watch...
OOOOH... I am SO doing that.
Time came for him to take it in for a checkup. He told them what kind of mileage he'd been getting, and they told him it was impossible. After that we started siphoning out about the same amount. He was, of course, livid, and got all over the dealer, like ugly on an ape, and we'd hear him accusing the dealership of switching carbureators on him, and otherwise screwing with his car. We never told him.
Well, we started pouring about 1/2 gallon of gas into his car every day, and his mileage skyrocketed. Later, when it was time for the car's first checkup, he told the dealer what kind of mileage he was getting, and they told him that was impossible.
After that, we started siphoning out about the same amount every fday. Used to hear him complaining to the dealer tht they'd changed carbureators on him, and in general screwing with his car. We never told him.