Black swan event
Having emigrated to the land of kangaroos before I was old enough to even know the name of a swan, I grew up believing all swans were black. On returning to my birthplace once I was old enough to earn my airfare, I discovered they also come in white. For a while, I just thought it was peculiar to see so many albino birds together, until I realised that all European swans are white. Of the two varieties, I would say the white are the slighly more unpredictable so what is this black swan event thing?