I have stumbled upon a very widely used in-joke by game developers. In pretty much every game ever made that has sound effects and togglable settings for them, if you turn on the music and turn off the sound effects, occasionally you'll hear sound effects anyhow, and very occasionally sound effects will turn completely on regardless of your setting. This is independent of gaming platform, game type, etc. I fail to understand the sense of humour of game developers though - perhaps this kind of thing is easier to program than easter eggs, nowadays? :P
Anyone in the know should either let me in on the joke or tell me why it's so difficult to get that code right. Is it just that nobody tests sound setting permutations much?