You're a typical human being sitting in typically brutal rush hour traffic. Nothing's moving except your blood pressure. How do you blow off the tension? You reach for the little black box on your dashboard and flip a switch, setting off the shriek of a grenade launcher, the rat-a-tat-tat of a machine gun or the detonating whir of a death ray. The noises may not be loud enough to be heard outside the car, but satisfaction never felt or sounded so good—which is why that little black box has become the season's trendiest adult toy. Called the Revenger, the device trades on the premise that inside everyone is a frustrated psychopath just waiting to make noise.

So far, the Revenger has blown off a lot of steam; since shipping began on Nov. 2,70,000 have gone out to retailers' shelves. That's relieved a lot of tension for David McMahan, 29, and Mike Grubbs, 30, who were fairly frustrated novelty peddlers until coming up with this gizmo. "We'll sell more of these in two months than anything else we've sold in two years," says McMahan, creative force behind Express Yourself, Inc., based in Charlotte, N.C. The two friends (Grubbs is the business brain) from the University of North Carolina say they expect to gross more than $10 million by the end of 1988. Bullock's department store in Los Angeles originally ordered 528 Revengers, then called a week later for 2,000 more ASAP. Not all of them went on sale. Bullock's executives use their Revengers to censure and heckle each other during weekly meetings. With Macy's, Bloomingdale's and Art Explosion among the other stores hawking the Revenger, tradespeople are calling it the hottest new Christmas item since Santa Claus started stuffing stockings.

Resembling an upscale radar detector, the gadget retails for up to $24.95—which might seem a bit much for a palm-sized piece of plastic that costs less than $10 to manufacture. But, hey, it's a fair price to pay for playing Rambo without guilt.