A: What are you wearing to Mary’s wedding?

B: The same dress that I wore to Jane’s wedding. I know I’m scraping the barrel. I just can’t afford anything new!

A: Who will be the maid of honor?

B: Lucy. That’s really scraping the barrel because all her best friends are already married.

Note: This idiom means to use something or someone that you do not want to use because nothing or no one else is available. This is an American idiom dating back to the time before there was refrigeration, when food was stored in barrels. When supplies ran low, the only means to get to the food at the bottom was to scrape it off.