For starters you don't want to be casual about 110 volts [0] and for seconds the systems that control heart rhythm use electricity. An electric shock can cause a heart to just stop some hours later (happened to a family friend as far as we can tell).
It is invisible, can kill and humans don't have the right nerves for pain to be an indicator of how bad the damage is. Electricity is hazardous and work on it should leave no scope for surprises.
[0] https://www.asc.ohio-state.edu/physics/p616/safety/fatal_cur...
I'm guessing at the exact mechanism, but I assumed the shock knocks the heart rhythm regulators out of sequence and the body can cope for a while but eventually goes in to cardiac arrest. There is some argument about whether symptoms spontaneously show after 12 hours [www.journalagent.com/travma/pdfs/UTD_18_4_301_305.pdf - linked from said article].
Cells have a bunch of interesting electrical properties - https://en.wikipedia.org/wiki/Electrophysiology . I recall a somewhat humerous story when they discovered electricity. Galvani made a frogs leg twitch and hypothesised something like electricity in the leg. Volta said the idea was bunkum and it was caused by the different metals being used for the experiment. Volta redid the experiment without the frog and someone did Galvani's experiment without the metal so everyone got to be right.
[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3096834/
[2] https://www.merckmanuals.com/home/injuries-and-poisoning/ele...
Basically it's 'possible' to get cardiac arrhythmias that don't kill you immediately and might kill you later. But not proven, so you're better off learning about not getting zapped than this possibility. Or learning CPR.
https://link.springer.com/article/10.1007/s00392-019-01420-2
Not electrical, but such syndromes seem to be real.
(We have 240VAC mains, but I guess an unexpected jolt of 110VAC would be sufficient to make me jump...)
My hand was in a shitty position kind of around a table leg, and the shock caused me to clamp down with my hand and kind of "chokehold" the table leg. It took me a lot longer than I thought it would to even register what was happening, and then to kind of throw myself away. I'd been shocked before, but this just kept going after I realized that it was happening and I just didn't know how to process it.
I ended up with some nasty burns on my hand, a really sore whole arm, and a scary realization of how it could have been a lot worse if just one or 2 things were slightly different.
Luckily, human skin is not highly conductive and neither are rubber soled shoes.
So if you are taking proper precautions and not kneeling on a wet floor while using all metal tools on bare wires when someone flips a breaker back on, then your risk is rather minimal.
In my experience, when encouraging people to follow safety rules you get better results with true examples that justify the rules than with exaggeration like this. If you tell a person one thing they know isn't true, they're liable to start thinking the other things you tell them aren't true.
240v might kill you if you're up a ladder, elderly, have an undiagnosed health condition, or are just plain unlucky. But it's not the guaranteed instant death that, say a 25kV shock is.
I did retire the extension cord, though.
10-20 amps? Not across your skin!
Usually a 220V zap at home won't cause instant death.
I've also been burned debugging a power supply for a GSM amplifier used in the test harnesses for a semiconductor fab (this time was carelessness, the power supply rails weren't taped off since I was probing it attempting to find a fault on the point-to-point wiring) that was powered at 240V and holy hell I do not recommend doing anything that stupid. If it doesn't have a safe way to repair, buy a new one.
I haven't personally been bitten by 240V but from people I've talked to who have, I don't intend to chance it happening.
All the rest of that day I felt weird. My skin felt too sensitive, my arms would twitch randomly, and I just felt kind of weak and vaguely dizzy all day. I did end up figuring it out and putting a rubber mat down which immediately stopped the electrocution problem. But I really don't like being electrocuted at all. It just isn't pleasant.
On topic, all our machines get locked and tagged before opening the electrical cabinets or working on anything where you might be exposed to live wires. It's enforced by worker's comp also. We get randomly inspected fairly regularly and one thing they check is that we have lockout keys and locks on every machine breaker.
