A favorite at Case Western Reserve University where I went to school in the late 1980s was the exploding electrolytic capacitor. In our dorms, there was a switched outlet in the bathrooms above the mirror over the sinks. Most people used it to plug in radios. When you left the bathroom and turned off the light, the radio would automatically turn off, saving electricity.
Well, we would go into the bathroom with a flashlight so we wouldn’t have to turn on the main overhead lights and energize the socket, stick a 47 uF (the optimum value, IIRC) cap into the socket, and wait for the next victim! Flip the switch, light goes on, cap goes boom!
It usually scared the #*$% out of him or her!
One time after a few beers, I didn’t have any caps handy, so I just wrapped some 20 gauge wire tightly around a pen and shoved it in the outlet. It worked nearly as well; instead of an explosion, there was a zap, and a burning, smoking, stinking coil of wire fell into the sink!
LOL just thinking about the good old days!