I used to have a "Christmas in July" party every summer. A few of us got together and played Christmas music, ate holiday-type goodies, and each taught the others a different craft project. Theoretically, it was so there was plenty of time to make more of those items for decorations or gifts, but mostly it was just because I love Christmas.
...or not eat cereal. Either way, as long as they grasp the fact I'm not cooking dinner, I'm fine with it. Sometimes it takes until after I've gone to bed for the night for it to sink in.