Dean Peterson noticed that the tenth step up on the staircase at his subway stop in Brooklyn was a fraction of an inch taller than the other stairs. That's just enough to make everyone whack it with their foot, because by the time you reach it, your feet know how tall it should be. According to the comments at vimeo, the stairs have been cordoned off with caution tape just today. Maybe this video had something to do with it. -via Metafilter