Oktoberfest

In 1950, the mayor of Munich, Thomas Wimmer, opened Oktoberfest for the first time in the traditional way, meaning by tapping a barrel.

An excerpt from the article 20 facts about Oktoberfest
Every year, the participants of the festival expect with great tension how many strokes will be needed for the beer to flow. Thomas Wimmer needed nineteen. Some mayors of the city today manage to do this with two strokes. The first mug of beer is traditionally given to the Bavarian prime minister by saying the words "O'zapft is!", which means “it is tapped.”