For many years in England, a roasted boar's head has been associated with holiday feasting.
The custom probably goes back to the Norse practice of sacrificing a boar at Yuletide in honor of the god Freyr. One story tells of a student at Oxford's Queens College who was attacked on Christmas Day by a wild boar.
All he had in his hand to use as a weapon was his copy of Aristotle, so he shoved the book down the boar's throat. Wanting to retrieve his book, the student cut off the animal's head and brought it back to the college where it was served for Christmas dinner with much pomp and ceremony.
Note that it is the Reed tradition to stand during the boar's head procession.