Well, I always celebrate the Annual Computer Security Applications Conference (ACSAC), which is always in December. Great people. Great technical content. A conference committee that is like family. Wonderful food. Interesting locations. What more could you want?
[Wait, you mean there are other holidays in December? Well, I don’t celebrate Christmas (I observe that it is on the calendar), and Chanukah moves around. New Years Day is in January. So I guess it is ACSAC.]