A wassailer is one who takes part in riotous activities. Not too old a word, appearing in print in the 14th century. Milton complained "I should be loath to meet the rudenesse and swill'd insolence of such late wassailers." Bah! Humbug!

Seriously, the folk practice of caroling has disappeared in North America and probably would violate some ordinance. When I was a kid, in some more rural parts of the country, there were still a few people who would ride (greater distances here) from house to house, singing carols, and being invited in to receive a drink or bit of food. No wassail bowl, but a few jugs.

Nowadays, some people gather at home with friends, but most go to a commercial establishment to eat, dance and drink.