Kids, don't do this at home. I've zapped myself good with a camera capacitor working on a coilgun, and it can be pretty dangerous.
Remember, that while commercial tasers can produce 100k volts, they are designed to do so at incredibly low amperage, and even those are not perfectly non-lethal. The human body can be killed by mere milliamps of electrical energy.
There are no truly non-lethal weapons -- only less lethal ones. Heart attacks, neurological damage, burns, and blunt force injuries can all occur even in previously healthy individuals. Also, note that every police officer trained to use a taser is trained to only use such a weapon when they have backup with a real gun : tasers can't do much to heavy clothing or a determined attacker.
I don't quite share the above poster's fondness for OC/CS spray (I've had those sprays blow back in my face, and I know people can simply ignore them), but to each their own.