Water-seller's cry on Arrakis. Sook is a market place. (See Ikhut-eigh!)

Quotation:

The banker smiled. "They call me Soo-Soo because I'm financial adviser to the Water Peddlers Union." And, as Jessica continued to look at him without comment, he added: "Because of the water-sellers' cry -- 'Soo-Soo Sook!'" And he imitated he call with such accuracy that many around the table laughed.