Why all unset pins of my Arduino Uno are outputting 2 volts?
The electric shocks being felt is due to leakage current from the laptop's switchmode power supply. All unearthed mains powered switchmode plug pack power supplies leak a few micro amps and voltages in excess of 80 volts AC as measured from the plug packs output socket to ground will be observed when measuring with multimeters having 10 meg ohm input impedance.
The solution is to have the GND pin of the arduino board connected to earth. Here in Australia all computer power supplies are grounded via the 3 pin power plug.