"Drop the ball" means "to make a mistake, to fail". Example: Thomas dropped the ball when he forgot to pick his girlfriend up at the train station. #idiom #idioms -Pinterest Repinned by Chesapeake College Adult Education Program. Learn and improve your English language with our FREE Classes. Call Karen Luceti 410-443-1163 or email firstname.lastname@example.org to register for classes. Eastern Shore of Maryland. . www.chesapeake.edu/esl.