A little girl gets angry at her father, and uses her index finger and thumb to make a pinching motion. No, she's not trying to hurt him. She's using iPad sign language to say, "I want you to be smaller."
PCs and cell phones required restricted motions, mostly clicking and typing. In contrast, the recent slew of computers, tablets, and smart phones utilize more expressive motions: swiping, flicking, squeezing. These gestures may enter the vernacular of common signs, like waving and shoulder shrugging, just as internet terms like 'lol' and 'brb' entered everyday language.
All great apes stick out their hands to beg for food, but only humans pinch if their friend won't share.
Image via Gawker