Anything you can do during the winter, preferably starting in December and ending on the 25th.
These games can include anything, most however, pertain to the cold or snow and include alcohol/egg nog.
Examples such as: case race with a case of beer, skitching on a sled behind a truck on the street, piling snow on top of a small car that you know cannot handle it, drinking, sitting in the backseat with the windows down with only underwear on to see which contestant bails first "freeze out 2011/2012!!!!"
Almost anything can be considered a Reindeer Game during December. All you really have to do is add some beer or egg nog. It doesnt have to exclude people like poor ol rudolph, but you can bring and sling whoever the hell you want.
Fletcher: You ready for these Reindeer Games?
Tylee: Fuck yes, December 1st! Lets get some beers and some sleds. Snow's-a-comin.