It shall be unlawful for any person owning or operating any restaurant, hotel, cafe, coffee shop, or other place where food is served, or any bakery or confectionery shop where food products are sold, to serve or sell any foreign eggs or egg products manufactured from foreign eggs without posting and maintaining in a conspicuous place where the customers entering any such place of business can see it, a placard or sign bearing the words "We Use Foreign Produced Eggs" printed or painted in legible letters not less than two inches (2") high.