Etymology
Supposedly, this word originates with a dispute at the Collège de France circa 1550, over whether to use a traditional French pronunciation of Latin or a reconstructed pronunciation of Latin. One of the points of most dispute was the pronunciation of qu, with the word quamquam exemplifying this: it was pronounced in reconstructed Latin as [ˈkʷam.kʷã(m)] but pronounced in French Latin as /kɑ̃.kɑ̃/ ("cancan"). After this debacle, a "cancan" came to be "any kind of scandalous performance".[1]
References
Allen, W. Sidney. Vox Latina. Cambridge U. Press 1978 p. 107.