Misuse of a stun gun can be grounds for legal action and may be a crime. Stun Guns are not toys. Stunts and games are best left to the 'experts' on You Tube.
Safety - The stun gun does not merely rely on pain for results. The stun gun works on the muscular and neural system. The effect on the heart is insignificant. It takes 5 to 10 minutes for full recovery.
Even if the assailant is touching you the current will not pass to you. There is no shock-back.
There are always anecdotal stories about stun guns and tasers. Upon close scrutiny you find that are ALWAYS mitigating factors and circumstances. Usually when you hear that a stun gun didn't work it was because the assailant was on drugs as an example.
DO NOT DISCHARGE THE UNIT INTO THE AIR FOR MORE THAN ONE SECOND. REPEAT FIRING FOR LONGER DURATION'S CAN DAMAGE THE UNIT AND MAY VOID THE WARRANTY!
Here's HOW STUN GUNS WORK and HOW TO USE STUN GUNS.