When you use the term ‘Chow Down’ you mean to sit down to eat.
Example of use: “Dinner’s ready; let’s chow down!”
The origin of the expression ‘chow down’ comes from the U.S. military, with first usage occurring sometime around WWII. The earliest printed use comes from a December 1942 issue of The Hammond Times in a story about sailors’ life on a submarine: “’Chow down, sir,’ a Negro mess attendant in a white coat informed. Served on navy blue and white china we put away steak, potatoes, peas, and ice cream.”