What is the origin of the idiom "scrape the barrel" and when to use it?

The origin of the idiom "scrape the barrel" can be traced back to the literal act of scraping the bottom of a barrel. In earlier times, barrels were commonly used for storage, and when the contents of the barrel were almost depleted, one would scrape the remaining bits from the bottom. This action was often associated with collecting leftovers or obtaining the last remnants of something.