Everyone started jerkin’ last year. When the kids returned from summer vacation, it was like they’d contracted some rare virus. A tsetse-fly bite in reverse, but rather than sleeping sickness, teenagers from Long Beach to Lancaster started getting geeked up … a dancing dominoes of flailing limbs, skinny jeans and fluorescent accessorizing. Jerkin’ at talent shows and on top of lunchroom tabletops. Jerkin’ in parking lots and bus stops, underground teen clubs, every single function (party), and, of course, on YouTube. Much of Los Angeles’ 18-and-under population was jerkin’ — presumably because they were the only ones young enough not to snicker at the term’s historically self-flagellating connotation.