Well, I don't tailgate that often anymore (I can't afford season tickets), but my parents do every weekend and I was brought up to do it their way. In fact, there was a brief interlude on the local news recently about tailgating and my dad got interviewed. Strange. Anyways, they go all out. My dad has specially equipped my moms car with outlets in the trunk so they can handle more than just 12 volt appliances. They take a plug in cooler, a small microwave and a blender for mixed drinks. There's also a small grill, of course, and a large picnic basket full of utensils and the like. A water cooler for washing your hands, three card tables (one long one), 2-4 foldable chairs, a foldable bench my dad made out of a piece of old stadium seating he picked up when they remodeled, a flag pole with flags and a whole backseat full of blankets, jackets and winter wear. Oh, and a silver ice bucket and matching silver candelabra with candles in our teams colors...they're staples.
Depending on whether it's an early or late game, either brunch or dinner will be served. The people they tailgate with coordinate the foods brought, but breakfast usually has some sort of egg dish, and always has mimosas. Dinners are usually burgers or steaks cooked on the grill, although one of their friends almost invariably makes soup of some sort. Once a year they boil lobsters in a turkey fryer. And of course, munchies all around.
Oh yeah, and my mom's car horn plays the fight song. It's terribly embarrassing.