Keep these foods at 40 degrees Fahrenheit or less, and cook meat until it's no longer pink inside. Everyone enjoys a juicy burger, but no one enjoys suffering from E. coli. If you're on the go, use a separate cooler for foods and drinks -- more than likely, the drinks cooler will be opened more often, allowing cold to escape. A full cooler will stay cold longer than a partially full one. And use the two-hour rule. If a dish has been sitting out for up to two hours -- less if it contains meat, eggs, dairy products or mayonnaise -- throw it away.