There's a lot to laugh about when it comes to music. Whether you're a band nerd, hobbyist, producer, metalhead, or whatever else, it doesn't matter. If you know anything about music, you can find some humor in making fun of it.
Now, I'm no expert on music. But it doesn't take a rocket scientist to become familiar with the basics. I grew up playing alto sax and I've played bass for a few bands. Casual stuff. If there's anything I've learned, band kids are ostracized for a reason, and people who pursue music careers often have rich parents. I also know a little bit of music theory.
Perhaps you've met a jazz player obsessed with theory? Maybe the lo-fi pop musician who uses a tasteless amount of reverb? You could just be looking for a music-related laugh. Here's a slew of music memes that cover everything under the sun.