I like to tailgate party.
In New Orleans, We have tailgate parties in the Parking Lot of the Superdome. 
We mostly do college football tailgating.
Tailgating come in all forms.  We bring the bbq, some bring rv's & campers !  But the orgin of tailgating is held on/near the tailgate of an automobile
Sometimes we don't even make it into the stadium.
That is true ! I see some people bring their own poison (beer, liquor, etc) to make the event 'sociable'.. More time is spent in celebrating before the game instead of After the win !
Some RVs start showing up mid week.
Yes, even before the event, such as the Sugar Bowl down here, you can see partiers spreading out their favorite team blanket, bringing hot dogs, beans and potato salad. Enough fixings for the team itself. Feed me !
Its all fun before the game and after a win, but sad after a loss.
Indeed. I think some people create their own food products based on their team. Like Wisconsin is known for its cheese, they wear wedges of cheese on their heads !