This is what a lightning rod looks like after it's done its duty. Why does a lightning bolt crush it like a fist crushes a beer can? Because of what's known as a "pinch."
Touchscreen pinching makes sense. It's undeniably intuitive, and pretty gratifying! And now it's everywhere—including places it shouldn't be, like the relatively tiny screen of the BlackBerry Bold Touch. This is like picking your nose with a mop.