Do you mean Christmas Specials for a particular TV series? If so, then;
As MC collects TV Series data from
www.thetvdb.com, it is a good idea to use the same method used on that site. The method they use is to put all Christmas Specials into Season 0 (zero) of the Series. The Episode number is then used to show the sequence of airing for the Special.
Doctor Who (2005), which is the new series of Doctor Who that started in 2005, as opposed to the old 1960's series, is a good example of how this methodology is used.
Take a look at
Doctor Who (2005) on thetvdb, and the
Specials page for that series.
If you are just talking about Christmas TV specials and such, then giving the program a Series name of Christmas would work fine.
Just be aware that if a program has a "Media Sub Type" tag of "movie", it won't appear in a TV series group, so you can't put all Christmas specials in there. You could change the Media Sub Type to "TV Show" for Christmas movies but that would have disadvantages, or you will have to build a view for say, shows with "Christmas" as a keyword, and then add that keyword to all Christmas shows. Or you could add a Genre of "Christmas" and use the existing Genre views. Either is probably the better solution for mixed TV programs and movies. But you would need to create a view that included Media Sub Types of both "movie" and "TV Show".
