Wanna steal my iPhone? Well you'll need a bigger knife than this! Oh, you do.
iPhones. They do so much. They search, they post, they push, they publish, they tweet, they call (sometimes), and now they stab. There are many ways this is a good idea: like when you get a package and you want to open it with your phone. Then there's the fact that you carry this near your femoral artery (the big one in your leg that will kill you if you nick it), the fact that it's just likely to anger any potential mugger, and the biggest drawback of all: imagine you're showing your friend the knife and you suddenly get a call and you put the phone up to your ear. Ta da! Ears-free calling!