Historians know for sure that the can-can dance emerged in music halls in France during the 1840s, but nobody is absolutely certain about the etymology of its name. According to one theory, it could be from the verb cancaner, which meant "to quack" and had figurative definitions of "noise" or "disturbance". Alternatively, it could be a duplication of can, a child's way of saying the French word for "duck", canard. Waterfowl aside, my favorite theory is that it could all stem from an argument between Latin scholars at the Collège de France in the mid-sixteenth century. The debate was over whether to use reconstructed Latin pronunciations or French pronunciations of Latin words. One of the most contentious terms was the Latin word quamquam, which should've been pronounced sort of like kwamkwam but the French pronounced it more along the lines of cancan. This became such a heated argument that the word cancan allegedly took on a new definition of "scandalous performance" in general - and that was later applied to the risqué dance centuries later. If true, that would be a really cool explanation.
Adam Aleksic, a rising sophomore studying linguistics and government at Harvard University, has been described as the internet's sixth most famous etymologist. He also has disturbing interests in politics, vexillology, geography, board games, conlanging, and law.