Tailgate

Tailgating. A primary part in the football experience. Fun. Exciting. A fans version of a pregame warm up. It warms a person up before a big game. The excitement that one experiences at a tailgate party stays with them as they enter the game. Tailgating is why I think the crowd is often more "into" the first half of the game. After a dull half-time performance, where a crowd sits and watches people dance, the second-half crowd is not as excited, usually. There are circumstances where the crowd is still pumped up, but from this blogger's experience, the fans in the latter half of the game are no comparison to the first half fans.
Think about it. Before the game, if you tailgate, you're surrounded by partiers, music, dancing, drinking and pick up games of parking lot football, not to mention, the booing of the fans of visiting teams as they approach the stadium. It's a party! It's really cool to see everyone all hyper before the game.
After halftime, fans were just sitting in their seats for 15 minutes, of course they aren't going to be all hyper like they were during the first half!
The players feed off of the crowd's excitement.
Therefore, tailgating is a vital part of the football experience! :)