The Wiggle is not a secret, not exactly; there is a detailed Wikipedia entry. But you would never know to Google “the wiggle” unless someone told you about it, right? You would never know the Wiggle was even a thing unless one of your techno-hipster co-workers, also in possession of a fancy flat-colored fixed-gear, upon hearing of your plight, said: “Dude … you know about the Wiggle, right?”
It is the path between the hills, a very specific route defined by two very special geometric characteristics: (1) It zigzags crazily, block by block, and (2) It is relatively flat. Back when San Francisco was still called Yerba Buena, it was, in part, the path of the Sans Souci Creek. It was the path, legend has it, that Juan Bautista de Anza took south from his fort in the Presidio circa 1776, looking for a bit of greenery among the dunes. It was, and is, the path of least resistance.