The directions said that a one-second burst would shock and disorient your assailant; a two-second burst was supposed to cause muscle spasms and a major loss of bodily control; a three-second burst would purportedly make your assailant flop on the ground like a fish out of water. Any burst longer than three seconds would be wasting the batteries.
...Reasoning that a one-second burst from such a tiny little ole thing couldn't hurt all that bad....I decided to give myself a one-second burst just for the heck of it. I touched the prongs to my naked thigh, pushed the button, and ... HOLY MOTHER ..WEAPONS OF MASS DESTRUCTION...@!@$$!%!@*!!!
I'm pretty sure Jessie Ventura ran in through the side door, picked me up in the recliner, then body slammed us both on the carpet, over and over and over again. I vaguely recall waking up on my side in the fetal position, with tears in my eyes, body soaking wet, both nipples on fire, testicles nowhere to be found, my left arm tucked under my body in the oddest position, and tingling in my legs. The cat was standing over me making meowing sounds I had never heard before, licking my face, undoubtedly thinking to herself, "Do it again, do it again!"
This might be bogus, as several readers pointed out (Thanks, all!). Here's what Snopes has to say about it. Link