Five volts isn't going to kill you unless it's surgically connected to your heart (medical device engineers need to take special care). The electrical resistance of the human body is high enough that five volts will not cause a harmful current to flow, unless the connection is surgically good.
It's overwhelmingly likely that her charger was defective. Example:
I did a little more reading and got the full picture.
Most phone chargers are 5v (at the least iPhone is), and draw current at up to 1A.
The 1A is most definitely capable of killing you, but it takes a lot of voltage to “push” that 1A past the natural resistance of the skin.
Ohm’s Law states:
I = E/R, where I is current, E is voltage and R is resistance.
Wet skin is said to have 1,000 ohm resistance.
So in the case of this girl, and assuming the worst case scenario of soaking wet hand grabbing the phone, we get:
0.005A = 5 Volts / 1,000 Ohms.
This isn’t anywhere near enough voltage and current to kill by a factor of 6,
0.005A = 5V / 1,000A * 6 = 0.03A (high end of the deadly amperage)
0.005A = 5V / 1,000A * 2 = 0.01A (the low end of the deadly amperage)
but it’s within reason that it could be deadly even from your cute little innocent little 5v/1A iPhone cube in the right circumstances. So be very careful around electricity, no matter how small, when also around wet areas.
(Someone let me know if I got this all right, I just poked around a little bit and did the math and it appears to be bad idea at even 5v when soaking wet)
Yeah.. If the output of the charger were floating, no shock. But if leakage occurred to the hot side of the line there was danger.