By Daniel Kline Fast-food chains have decided that no flavor is off limit and no idea is too bizarre. Fast-food chains used to (in the 1950s and 1960s) built their menus around predictability. McDonald’s (MCD) – Get McDonald’s Corporation Report and Restaurant Brands International’s (QSR) – Get Restaurant Brands International Inc Report Burger King literally started by making sure each restaurant offered the same experience no matter where you might be eating. That started to change in the 1970s as consistency gave way to customers wanting something different. At first, that led to innovations…