dumpster
A large metal container used to hold trash and garbage.
A dumpster is a large metal container designed for holding garbage and waste until a truck comes to empty it. You'll find dumpsters behind schools, restaurants, apartment buildings, and stores. They're usually made of heavy steel, stand about as tall as an adult, and have lids to keep out rain and animals.
When someone says they're dumpster diving, they mean they're looking through a dumpster for useful items that others threw away. Some people find perfectly good furniture, books, or food this way, though it can be messy and may not be allowed in some places.
The phrase dumpster fire has become slang for a situation that's a complete disaster. If someone says a project at school is a dumpster fire, they mean it's going terribly wrong in multiple ways at once, like a dumpster that’s actually burning: messy, smelly, and getting worse by the minute.