Sandwich board, advertising sign consisting of two placards fastened together at the top with straps supported on the shoulders of the carrier, or sandwich man. The sandwich board was a popular form of advertising in the 19th century, when merchants and tradesmen hired men to carry the placards up and down the streets (sometimes on horseback), promoting their goods and services to passersby. A-frame signs, also called “sandwich boards,” are a can’t-miss addition to any business space. Setting them up outside or taking them back in is a breeze, and they’ll get seen by almost anyone walking by.