 You just want to make sure that that food is kept hot. That way you can serve it safely and enjoy your cookout. Now, it's the opposite rule for cold foods. So if you're serving perhaps some kind of dipping sauce or a potato salad, something that's eaten cold, you want to make sure that you nestle it on top of some ice on a tray with ice underneath to keep that food cold. And as the ice melts, of course, replace the melted ice with new ice.