... because of the way they ripple beneath the skin like rodents scurrying beneath cloth. Or so I'm led to believe. Our classics teacher was rather fonder of contemplating the ripple of muscle beneath skin on taut young torsos than perhaps strictly necessary for appreciation of the culture of the Romans - but then again, given what the Romans got up to, he could just have been a believer in immersive studies.
Which goes no way at all towards explaining this most unusual moust unusual USB peripheral. It's a computer mouse with additional electrocution circuitry. You plug it into your computer, then wire up bits of your torso to the cabling, and it makes your muscles twitch through bolts of electricity.
Now, I know that such things have currency among the fitness fanatics (although I don't believe they do any good) and others who have their own special territories in the empire of the senses. If that's your bag, then by all means tuck into the tingle. But why on earth integrate the device with a mouse? Why not, oh, a keyboard or a desktop lamp or even just a stand-alone peripheral? The description doesn't mention whether there's an open API - it could lead to interesting experiments in error reporting or productivity feedback, or attracting people's attention to urgent emails.
Or gaming. Now there's an idea.