/diy/ - Do It Yourself

Can someone please explain to me what kind of voltage these things actually produce?
There's so much misinformation like "it's not the volts that kill you, it's the amps" and other such bullshit that confused me about electricity for years and made me think voltage and current were two separately controllable properties rather than them being completely dependent on each other.
Obviously these things can't induce 50,000 volts across you or whatever people claim because due to ohms law they'd need to be capable of supplying a whole neighborhoods worth of current to make that potential difference possible.
So what is the actual sustained voltage and current that one of these creates across and passes through you?