Like notaries, witnesses aren't generally required in order for a contract to be legally enforceable. However, each state may require special kinds of contracts (e.g., real estate deals, wills, and marriage agreements) to be witnessed by a third party in order to be binding.
McDonald's, apparently, use red and yellow because red=fast and yellow=hunger (hence fast food!). Remember also that meaning is what we create. It does not exist in the color itself and individual meanings may or may not exist in different cultures and individuals.
Jewish people fast for 25 hours and spend the day in continual prayer on the day. Traditionally a meal of rice, kreplach dumplings, round challah bread and chicken or fish is eaten before the fast. Many will choose to wear white as a symbol of purity but no make-up, perfume or leather shoes should be worn.