from The American Heritage® Dictionary of the English Language, 4th Edition
- n. Two large boards bearing placards, hinged at the top by straps for hanging over the shoulders with one board in front and the other behind, used for picketing or advertising.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A person-sized, wearable billboard or advertisement consisting of two printed boards strung together so that they hang over the shoulders, thereby sandwiching the wearer.
- v. to advertise or campaign using a sandwich board; to wear a sandwich board.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. signboard consisting of two hinged boards that hang front and back from the shoulders of a walker and are used to display advertisements
From sandwich + board (Wiktionary)