Given the resistance of skin, it's unlikely to hurt you- V=IR and all, and it only takes current on the order of a tenth of an amp to kill, if it passed through your heart or head. Still not a good idea. OTOH, you can pass high-voltage, high-current tazer darts through your stomach, hand or thigh all day and feel nothing but pain because the current is siezing up muscles other than your heart.
There's an urban legend about a man who killed himself with a 9V battery by jamming the probes through the skin on his thumbs- would have put about 90ma through his heart, just enough to kill. http://www.darwinawards.com/darwin/darwin1999-50.html
Normally, the body has an resistance of about 500kOhms or more (varying wildly), but the resistance goes down drastically if the skin is wet- electric chairs use probes dipped in saltwater to reduce the resistance to about 5kOhms. Hence why we put GFIC in kitchens and bathrooms but don't bother anywhere else- 120V is not normally enough to kill. 5mA is generally the threshold for danger.
[This message has been edited by SteveFehr (edited 03-24-2005).]