Bike thieves be wary. A pair of San Francisco entrepreneurs are developing a way to stop you—and you'll probably think it really stinks. Daniel Idzkowski and Yves Perrenoud created a steel U-lock called the SkunkLock that emits a noxious, vomit-inducing odor into the face of the person attempting to cut it. The acids in the pressurized formula are food-grade, sharing the same properties as those found in fowl-smelling Swedish fermented herring. Inhalation won't cause permanent harm but it does lead 99 percent of people to throw up uncontrollably. As your angle grinder just starts to break through the lock's steel,...