Mental detector
A mental detector is an invention to protect airplanes from terrorists. It detects the mental state of all who pass through it, and an alarm is set off whenever anxiety is detected. This is not only useful in preventing smugglers from passing inspection, but prevents those who have arrived less than 2 hours before their flight from having any chance at all of making that flight.
The use of mental detectors has also extended to schools, military and government facilities. In schools, it is responsible for preventing anxious students from taking their exams, tardy students from arriving to class at all, and sober students from arriving on the first day of class. It also is a useful tool in preventing bullying, since those bullied cannot pass through the mental detector without setting off the alarm. In military facilities, the mental detector has greatly reduced the number of people attending boot camp - to the point that boot camp is now held off-site, outside the perimeter of the mental detector.
In government facilities, the mental detector has been responsible for a number of absentees who would have been merely tardy had the system not been installed. It also prevents government conspiracy types from entering the building, for they are always anxious around government buildings.