The Barrison Sisters were a risque Vaudeville act who performed in the United States and Europe c. 1890 - 1910.
The Barrison Sisters, c. 1890s
Lona, Sophia, Inger, Olga and Gertrude Barrison were actual sisters (many "sister" acts in Vaudeville were not) of Danish or Danish American descent. They were said to sing in high squeaky voices, and dance with middling ability. They achieved notoriety, however, by ingenious use of double-entendres and carefully pushing the envelope of what was allowed on stage.
Lona Barrison in Berlin, 1903
A similar act was later performed by the Machinson Sisters.
The Barrison Sisters were advertised as The Wickedest Girls In the World.