Parties that usually center around a group of people who tailgate to a football game (originated in the South). Once there a party, typically, with food (barbeque or grilled) and alcohol, is held in the parking lot.
Recently tailgating parties have begun to take place at other sports games, symphony performances, and nascar races all over the U.S.
"What started out with a few sandwiches and a couple of beers before the game...has evolved the tailgate party into great American sports tradition...
A group of friends can drive to any outdoor setting, park their cars and pull down the tailgates - get out the grills and prepare a feast!" --Chiff.com