Oh I get it you guys just don't understand how to make a human body conduct.
First things first, old farts that have dried up over the years are much harder to get to conduct than fresh pink little babies. Its the water content. So you might want to start with a spare baby you have lying around the boat if this is your first attempt.
Lick your little finger and thumb, firmly place your little finger on the negative terminal of a 12 volt battery. Lightly stroke your thumb on the positive terminal. Finger must be on the same hand and you are looking for a slight electric sensation. It is similar to placing a 9 volt battery on your tongue. You should be impressed that your body is now conducting the awesome current of upwards of .00001 amps and your nervous system can still detect it. note the compleat lack of heart stoppage or sparks.