Because it is traditionally eaten on Christmas eve.
wensleydale
carrot cake
Christmas Pudding and Dundee Cake.
it is crab or lobster
Since it is summer in Argentina on Christmas day, the meal is often served in the garden or may be a barbecue. Traditional foods are roasted turkey, roasted pork, stuffed tomatoes, Christmas bread, and Christmas pudding like 'Pan Dulce' and Panetone. The main meal is traditionally eaten in the evening on Christmas Eve.
Geese are normally eaten!
Italy
That would be "Italian Christmas Cake". Yum
United Kingdom, Canada and many Commonwealth Countries
Traditionally people in Japan will eat something called a Christmas Cake on Christmas. A white cake with white frosting and red accents. But it is not eaten just for dinner, but as a treat. Christmas is not celebrated in Japan as it is in the U.S.
They can be eaten everyday but the day they are traditionally eaten of Good Friday