cancan (n.)

also can-can, "A kind of dance performed in low resorts by men and women, who indulge in extravagant postures and lascivious gestures" [Century Dictionary, 1895], 1848, from French, a slang or cant term possibly from can, a French children's word for "duck" (see canard), via some notion of "waddling" too obscure or obscene to attempt to disentangle here. Or perhaps from French cancan (16c.) "noise, disturbance," echoic of quacking.