Meet the Stinger Tactical Whip: It’s just a couple feet of steel cable sheathed in plastic, but I know from painful personal experience how much this thing will hurt (click on the video down at the end and jump ahead to about 7:55 to see the guy take a mild stroke across the back with it, the welt it makes, and the way he winds up on the floor!).
Lily and I have a similar homemade toy: It’s a handle with two loops of plastic-sheathed cable. It’s nasty; with very little effort on Lily’s part, it leaves me covered with U‑shaped bruises that make me look like I got trampled by a horse. I hate to think the damage either one would cause if you hit your victim hard.
Stinger’s version sells for $39.99, which seems a bit high considering it’s just a piece of cable with a handle. It does have a window punch on the other end of the handle, but that’s a feature worth nothing if you want to do some impact play with this.
It’s a cool idea, but if you want one I’d recommend going to Home Depot and buying a couple feet of cable.