The Stars and Stripes Forever is a song you should hope you never hear while under the Big Top at a Circus. This song is used as the "disaster march" by most of the North American companies, and it is only played when something has gone horribly amiss. Upon hearing this played, all Circus personnel outside the main tent are supposed to immediately begin evacuation. This tradition began when live bands were used during performances, and is still used today, even by the big names in the business, albeit on tape instead of in person.
If you are attending the Circus and hear this song, it would be a good idea to leave immediately.