I can't see every film out there so this spoiler was sent in and spoiled by: "wormwood"
Ben Afflek plays Rudy who is almost finished with his prison sentence of five years for "grand theft auto". His roommate in the slammer is Nick. Nick is in for 2 or 3 years (I can't remember) for killing someone, go figure. Nick and Rudy are going to get out of the pen on the same day which just happens to be a couple of days away. Nick has been writing letters to this gorgeous gal named Ashley (Charlize THERON) and can't wait to get out because she's rented a hotel room for the holidays. Rudy is mildly jealous of Nick but states that all he wants is a hot chocolate and some pecan pie.
Then Nick gets knifed "saving" Rudy in this prison cafeteria riot by this guy that thinks Rudy ratted on him.
When Rudy leaves prison he pretends that he's Nick, goes to the hotel with Ashley and does her.
Then her brother Gabrielle (Gary SINISE) and his trucker pals beat the crap out of him telling him that they know about "The Tomahawk" so Rudy starts claiming that he's not Nick.
The Tomahawk is a casino on an indian reserve that Nick worked at two years ago. Rudy gets into a lot of uncomfortable situations since he's not really Nick and knows nothing about the casino.
We find out before the job happens that Ashley isn't really Gabrielle's sister but his girlfriend and that she's been sending letters to Nick in hopes to find out about something like this casino. Nick talked about how he wanted to break into it in his letters. She's in a pool with Gabrielle and takes her bikini top off, that's right, there are breasts in this movie.
The master plan for robbing the casino is to wear santa suits. So five guys go into the casino wearing santa suits. It eventually gets into shoot out and everyone dies except Ashley, Gabrielle and Rudy.
There is a pretty funny part before the shoot out that should be mentioned. Rudy is playing blackjack and he keeps arguing with this old man beside him. He calls him a jinx and then starts telling him to go away and then starts yelling "You're old!!, You're old!!!".
Ashley and Gabrielle take Rudy to this big cliff to go kill him. Then we find out that Nick isn't really dead and this whole thing is a big master plan. Nick was in prison for murder, and apparently the murder was in defense for against his girlfriend Millie at the time. But Ashley is really Millie and her and Nick have setup Rudy and the truckers so they wouldn't have to be involved in the robbery.
Everyone dies except Rudy, who walks home in a santa suit with two bags full of money. He puts a bundle of money in every mailbox on the way home and makes it home for Christmas dinner.