Repeal Day is important to so many Americans who know nothing about it. On December 5, 1933 the state of Utah became the final state needed to ratify the 21st Amendment to the Constitution. The 21st Amendment repealed the 18th Amendment -- Prohibition.
The 21st Amendment ended what was a disastrous attempt at social engineering, as well as an unfortunate example of unintended consequences. If you want to read more about this important period of American history, I highly recommend Last Call by Daniel Okrent. If you want something less intellectual, watch The Untouchables, listen to music from great Prohibition era artists such as Louis Armstrong or Billie Holiday, or look at the photo of Betty Boop (whose cartoon character first came onto the scene during the tail end of Prohibition).
Want to celebrate Repeal Day with style? Have a cocktail that someone created in the United States during Prohibition, e.g. the Scofflaw or the 12 Mile Limit, or have a cocktail an American created outside of the United States during Prohibition, e.g. the Mary Pickford or the Boulevardier. Just have a drink.
If there ever was a day of celebration for Americans who choose to imbibe, Repeal Day is it. A toast to the 21st Amendment!