While being at the high-school, I reconverted a technology class project consisting in a little sound generator into a electric "teaser". For doing that, I chained some transfomers to the sound output in order to rise the voltaje to a "shocking" level -- I already knew that the current decreased as I increased the voltaje, so it was not going to be harmful, but I really had tons of fun :-)
By the way... IoT world includes multiple spooky protocols --Zigbee, Wifi, Weightless, Bluetooth...-- and a plethora of different EMC and RF spectrum regulation that applies in each geographic zone. If you add a crowd of --patent-- trolls jumping around, IoT is pretty scary by its own!!!
I don't quite remember what kind of things I developed in that time period (which may be a good thing), but I have been wanting to develop a device that sets on the center console of a car that has control levers like an airplane, and has appropriate sound effects. This is one reason I'm digging into the Arduino. (Now if only my wife would go and make us independently wealthy so I can have more time for these little projects).