One of the other teachers at a College where I worked many years ago built a box with a BIG sign saying DO NOT SWITCH ON! It sat outside the staff room.
Inside was an electrolytic capacitor connected across the mains.
Sooner or later one of the apprentices would operate the switch, blowing the capacitor with lots of noise and smoke (and the sound of running feet).
Later, this teacher discovered digital electronics (yes, it was that long ago) and built another box with the same label. When the switch was operated, it emitted a loud noise. When the switch was turned off again, the volume doubled and kept doubling each time the switch was operated.
Hours of amusement for the staff counting the number of switch operations before the sound of running feet started.
Happy memories.
Jim