The ability to cause nasty burns due to extremely high currents as nothing to do with the ability to cause electric shocks.
Yep, this is exactly what I was worrying about.
Even my biggest one is only at 700F 2.5Volt, but with the internal resistance is about 4 mili Ohm, an accidental short across the terminals by a small conductive metal will make it glow bright red or even melt it.
Definitely I don't want this to happen unattended.
In practice, single supercaps are mostly harmless.
Yes, in theory they can dump hundreds of amps if shorted. But in reality at just 2.5 - 2.7 volts the short must have a really low contact resistance with the capacitor terminals for any significant current to flow. This requires some determination and is quite unlikely to happen accidentally.
I tried shorting a supercap with crocodile clips, expecting the wire to become red hot in an instant. I was dissapointed when all I managed was to get it lukewarm. The wire-clips assembly had a total resistance of 0.7 ohms. That's low, but at just 2.7 Volts the result is an unimpressive 3.8 amps.
Of course, if you string several caps in series and get a working voltage of 12 Volts or more, things can get really dangerous.