The Ross Sisters were a trio of female sibling singing dancers consisting of Aggie Ross, Elmira Ross, and Maggie Ross, (whose real names were Veda Victoria, Dixie Jewel and Betsy Ann Ross).
The Ross Sisters performed as a 3-part harmony trio, in which they also danced and did acrobatics and contortionism.
Their public attention peaked during the 1940s, during which they were featured prominently in the film Broadway Rhythm.
The crazy contortionism really begins about a minute in. The still photos don’t do it justice.
Fair warning, though – be sure to turn the audio down or your brain will probably be possessed by Azathoth. Or a potato salad. One of the two.
Via on YouTube.