This is the Twitchy Kitty Electronic Tail designed and sold by ThinkGeek ($35). You just clip it to the back of your waistband, and two AA batteries keeps it swishing back and forth for hours and hours. Of course, if you're a hardcore furry this thing probably looks like a joke to you. Please, I can see the battery box! You're completely taking me out of my furry fantasy. I need REALISM. And if that involves scouring the roadside for a roadkilled possum and having its tail grafted above my butthole, so be it. I'M JOKING, a skunk or racoon tail will do just as long as it doesn't have any visible tire tracks.
Thanks to Cyndi, who offered to buy me one, which I graciously declined because I think I might really be on to something with this roadkill idea.