the.com/tailgate

means To party out of your car trunk in a parking lot before (or instead of) actually going to the game.

from Literally the hinged board at the back of a wagon or truck — the 'tail gate' — which farmers dropped to load cargo. By the mid-20th century, Americans were dropping that same gate to set up food and grills before football games, and the vehicle part loaned its name to the entire ritual of eating in parking lots.