[BoxOfRain]

You'd have to really try.

10 milliamps across your heart can kill but using Ohm's law we can calculate 3V / 0.010 A to get a resistance of 300 ohms. This means you're probably still going to have a bad time if you apply it directly across your heart during open-heart surgery but other than that 3 volts just isn't enough to drive a lethal current through your skin.

[jcdny]

Which is why if caught in a lightning storm you should crouch with feet together and why I try very hard to only use one hand when doing something that might have the potential to shock me.