Can be used as part of an expression. For example "What is this, musical chairs?" Used to express the feeling that everyone/everything is changing around you unpredictably. If Orion and guinea-pig change their IRC nicks to Sirius and Orion, it makes you wonder whether we are all involved in a cosmic game of musical chairs and nobody bothered to let you know. In fact, Orion and Sirius and guinea-pig are the same person. Strange world.