Syrup of squill is a liquid used as a condiment for foods.
In 2374, Quark discovered that the Balancar had faked a drought on the planet to drive up the price of syrup of squill. Quark went to Balancar's Agricultural Consortium's chief accountant with evidence that he had bought a pair of Ferengi rain slippers and threatened to expose the Consortium's plot if he did not provide Quark with a shipment of syrup of squill. Quark returned to Deep Space 9 triumphant with three crates of syrup of squill. (DS9 episode: "The Magnificent Ferengi")
In 2376, Quark heard that Balancar's new Prime Minister had raised tariffs for all exports from the planet, driving up the cost of syrup of squill. This turned out not to be accurate and Ro Laren threatened to arrest him for fraud if he sold overpriced squill to a customer. (DS9 novel: Ferenginar: Satisfaction is Not Guaranteed)