It's possible you're thinking of a specific idiom that includes "your", but you haven't provided the full phrase.
If you can tell me the full idiom, I can help you understand its origin. For example:
* "Your guess is as good as mine": This idiom likely emerged in the late 19th century as a way to express uncertainty or lack of knowledge.
* "Your time is up": This phrase originated in the context of time limits, particularly in games, competitions, or speeches.
Please provide the full idiom, and I'll be happy to explain its origin!