When Madonna sings on a shiny crucifix, she’s martyring herself for the children of the world. When Christina Aguilera drapes herself across a piano, she’s insisting she’s “trouble.” But if Brazilian Girls’ singer Sabina Sciubba was making a statement by appearing at Club Soda for this summer’s Montreal Jazz Festival wearing a blindfold and very high heels, dragging a ball and chain, and apparently struggling with a straitjacket, her aim was much less obvious.