I think this would be funny

Imagine being in a band. Imagine that your band gets signed to a small record label, puts out an album, and tours locally. Your band gets the attention of a big famous band like Metallica, and Metallica asks you to be the opening act on their upcoming tour.

The problem with opening for a band like Metallica is that almost everyone in the audience loves Metallica more than any other band. Metallica fans pay a lot of money to see them, and they all probably want your band to hurry up and finish your set and get the hell off the stage as quickly as possible so they can see their favorite band.

So during your first show opening for Metallica, you have a few of your friends in the crowd, and after your set is finished, your friends cheer wildly. No one hears them or cares because the lights come on and the crowd is so excited to see you leave the stage that they start cheering because they're finally going to get to see Metallica.

Your band leaves the stage, but hears the cheering from your friends and the rest of the fans excited about seeing Metallica. So maybe because you think they're all cheering for you, or maybe just as a "fuck you", you decide to come out and play an encore.