That's an excellent and important question! When it comes to a truly *completely* fireproof outdoor trash can, the direct answer is that most standard "trash cans" are not designed to be 100% fireproof in all circumstances. However, what you are looking for—and what is readily available—are highly fire-resistant or fireproof-rated containers specifically built to contain fires and prevent them from spreading.
For ultimate safety, you want a heavy-duty metal trash can, typically made of galvanized steel or aluminum. These are the closest to "fireproof" for outdoor use. Plastic bins can melt, but a sealed metal can will contain a small fire (like from discarded ashes or hot coals) by depriving it of oxygen. Look for cans labeled as "hot ash" or "fire-safe" trash cans, often sold at hardware or home improvement stores.
A key tip is to never place a metal can directly on a wooden deck. Always use it on a non-flammable surface like dirt, gravel, or concrete. For added safety, consider a dedicated hot ash can with a tight-fitting lid and insulating feet if you dispose of fireplace or grill ashes.
So, while no can is indestructible, a sturdy metal can is your best defense. It protects your property by containing potential fires safely. Remember, the goal is fire *containment* and *resistance*. Always let ashes cool for several days before disposal, and never use these cans for flammable liquids.