Pane sciocco (also called pane toscano outside Tuscany) is a variety of bread commonly found in Tuscany, Umbria and the Marches, three regions of Italy. "Sciocco" means "without salt" in Tuscan and "stupid" in modern Italian.
Tu proverai sì come sa di sale lo pane altrui, ...
Being different from the others kinds of Italian bread, pane sciocco doesn't have salt added. Probably the reason for this comes from around the time of the 1600s when salt was a rare product, with a high cost.
Pane sciocco is often eaten with typical Tuscan condiments like cheese, ham or sausages, which are famous for being salty.