I've mentioned this before, but when I was a student we were discussing surrealism and I said that most musicals, in which people suddenly burst out into a song and dance with complete strangers who somehow know all the words and steps, take some beating ... so a group of us decided to do it. We would all go into a pub/bar in ones and twos over an hour or so and then when we were all gathered off we would go, with people joining in apparently at random from different corners of the room.

Perhaps because we we are much of the same age, no-one reacted at all, but most were probably thinking "Bloody students again"