The Hebrew expression “prove that you don’t have a sister” is commonly used to describe situations where an allegation is made without any evidence, and it becomes incumbent upon the subject of the allegation to prove that it’s false.  (This column was originally published in the Times of Israel on Nov 26, 2021.) 

Prove that you don’t have a sister | Susie Becher | The Blogs (timesofisrael.com)