His character also forgot fuses exist and that you can’t kill yourself with a toaster in a bath
In modern toasters in modern homes. The trope absolutely did stem from this being possible in the past at least. Many toasters would not have a fuse, and older homes and electrical wiring did not have GFCI outlets in bathrooms and kitchens. So you could be electrocuted until you tripped the home circuit breaker. And jamming that into the closed position would be all you have to do before your electro-dunk in that case.
Why wouldn’t you feel pain as you die?
Well I almost died from a massive head/neck/back injury. I lost all memory from around 2 minutes before until 3 hours after it happened. I highly recommend going out this way. Seriously I was just having a great morning riding my bike to work. Then a guy is pulling a big piece of glass out of my face in the hospital. It is kinda like anesthesia but even more disconnected and black void space.
I had a stroke in my sleep. I do not recommend going out that way. The nightmares it caused was horrible. It made me realize dying in your sleep isn’t the best way to go that we all think it is.