Some ‘orrible unwashed anarchists that I know of in London have a regular thing called the Circle Line party.
They get on a train and party, with drinks, music and stuff and have a fun time. Even the commuters tend to lighten up a little and as they keep quiet in the stations, they usually get a fair bit round before the police come and turf em off.
Sadly, there is no Circle Line in Munich and I doubt VERY much that many Germans would join a spontaneous party on the U-Bahn.
BUT, what about a mass U-Bahn pub crawl?
Station to station and we go for a drink in a pub at each stop?
Any takers?