Can you put an empty coffee cup in the microwave?

Here's why:

* Metal: Most coffee cups are made of metal, and metal can reflect microwaves, potentially causing sparks or damage to the microwave.

* Heat: Empty cups can overheat rapidly in the microwave, potentially causing them to crack or melt.

* Fire Hazard: If the cup contains any leftover coffee grounds or residue, it could catch fire in the microwave.

In short, it's best to avoid putting any empty cup, especially metal ones, in the microwave.