meat-and-three
n.— «Meat-and-three is simply what people call a lunch of one meat and a choice of three vegetables. Meat and three, you got it. Over the years, mom-and-pop cafes were known for this simple, special food. While fast-food establishments have taken some share of this market, you’ll still hear people who treasure the memory and want to keep meat-and-three going as long as lunch is a part of everyday life.» —“The Back Nine features favorite meat-and-three” by Jo Ellen O’Hara Birmingham News (Ala.) Mar. 10, 2006. (source: Double-Tongued Dictionary)
To me, “meat-and-three” refers not to the meal (which could be dinner as well as lunch), but to the restaurant where such meals are served. Similar to “blue-plate” to mean a restaurant or diner that offers blue plate specials.