brass farthing

Something that is worth very little, nothing, or next to nothing. Refers to farthings (obsolete British units of currency, worth one-quarter of a penny), formerly made from a copper alloy (brass). Usually used in the negative, and most often in the phrase, "not worth a brass farthing." Primarily heard in UK. I didn't get a brass farthing for all the work I did on that project. This old car isn't worth a brass farthing. If I had a brass farthing for all the times I heard that excuse, I'd be rich by now.