This problem can be modeled using a battery, a tub of water, and the worst-case scenario that a person connected in parallel with that tub of water. (ie. that person is directly touching the leads of the battery in the tub of water).
First of all let's assume the battery is 20V DC.
The
conductivity of tap water is typically around 0.5 mS/cm. This translates into 2kOhm/cm. The leads are about 1 cm apart, so in effect there's about 2k Ohm between the two leads. 20V / 20 kOhms = ~10mA. This is your tub of water.
Now the person. Typical measurements
suggests that a hand immersed in liquid is about 200 Ohms. Since we're dealing with whole body conductance here, the electric flow path is through one hand and out the other, doubling the resistance resulting in 400 Ohms of resistance. This is actually somewhat conservative, Wikipedia has it listed at 1 kOhms. Since the resistance is about 5 times lower than the tub, then 5 times the current flows through the person. This results in a current of about 50 mA; causing a tingling feeling at best. Nowhere near
300-500mA of DC current needed to cause a fibrillation.
Make sure she runs the laptop on battery. If she runs it on mains and the charger PSU brick gets pulled into the bath that could be game over...
Most bathroom outlets since at least the 80s have been equipped with GFCI to preclude against this possibility (except they had hairdryers in mind). It is not likely to be a GG, although she might feel a nasty shock.