Why did my coffee make a buzzing sound when sitting on desk?

It's likely that the buzzing sound you're hearing from your coffee is not coming from the coffee itself, but rather from something else near it. Here are a few possibilities:

* A nearby electrical device: The buzz could be coming from a phone charger, computer, or other electrical device plugged in near your coffee.

* A vibrating object: A phone, tablet, or even a nearby speaker could be vibrating and causing the sound.

* Acoustic resonance: The sound might be resonating from another source, like a nearby vent, air conditioner, or even traffic outside.

* A faulty electrical outlet: A loose connection in an outlet could cause a buzzing sound.

To figure out the source, try these steps:

1. Remove nearby objects: Take away any phones, chargers, or other items near your coffee to see if the buzzing stops.

2. Change the location: Move your coffee to a different spot on your desk or even to a different room to see if the buzzing follows.

3. Listen carefully: Pay attention to when the buzzing is loudest and if it seems to be connected to any other sounds.

Let me know if you have any other details about the buzzing sound, and I'll try to give you a more specific answer!