Every day :-)
Offically there is a "Tag des Bieres" (Day of beer) on April 23rd. But it's not celebrated in a special way.
beer
There is no special day. But many German cities got annual festivals where wine or beer (depends on the region) is celebrate.
In Germany, Labor Day is celebrated on May 2. There are often maypoles, festivals, German food, and beer. Violence has become a game of Labor Day celebrations in Germany since the late 1980s. The celebration began on May 1, 1933 but was outlawed by the government the following day.
German unification day is celebrated on the 3rd of October every year in Germany.
Octoberfest is a festive season of the year. The major festival is a 16 day festival celebrated in Munich, Germany. The festival includes the consumption of beer, pretzels, sausage and other German foods.
VE Day is celebrated in May, because the last major capitulations of German resistance came in May 1945.
Groundhogs Day was first celebrated in Pennsylvania many many years ago - in the 18th and/or 19th centuries. It is suspected that it is from a German lineage.
In Germany Easter is celebrated on the same day as everywhere in Western Christendom.
German who started brewing beer in Dunedin in 1857
Bier
A beer hall is a large German public house which specializes in beer.
The traditional German beer girl outfit is called a dirndl.