Sharing a drink at the bar. Another Christmas custom! A luxury, no doubt, but a hot punch (alcoholic or not) keeps the cold out. Shakespeare provides us with one of the most poignant songs of Christmas cheer at the end of Love's Labours Lost:

When Isicles hang by the wall,
  And Dicke the Shepheard blowes his naile;
And Tom beares Logges into the hall,
  And Milke comes frozen home in paile:
When blood is nipt, and wayes be fowle
  Then nightly sings the staring Owle
Tu-whit
To-who. A merrie note,
While greasie Jone doth keele the pot.

Greasy Joan, stirring a pot of ale, mixed with spices and with crab apples bobbing on its surface, broods in the background of our Christmas celebrations like a primeval matriarch. Why not join her? Greasy Joan was almost certainly concocting a drink know as 'Lamb's Wool'. The recipe for this delicious old drink can be found at
http://recipes.alastra.com/holidays/lambs-wool.html

And if you want to sing while drinking, then there is an excellent collection of Wassail words and tunes at http://www.geocities.com/CapitolHill/5567/wassong.html#main