The song is over. The drummer starts going BAPPITA BAPPITA BAPPITA and the guitarist goes DOODLE DOODLE DO and the bass player goes BWAAAAABABABABA up the neck and the keyboardist plays seemingly random notes on the piano but it's also probably in the correct key and the lights are going nuts and then they all look at the drummer and she hits the crash cymbal as they all land on a quick chord and now the song is really over. Who invented that?
Did it originate with rock and roll, is it a jazz thing or did, like, the orchestras in Mozart's day all start playing crazy stuff at the end of the requiem before some guy blew out all the candles?