I fall asleep at the drop of a dime

This wonderful congruent conflation is a mash up of  “at the drop of a hat” and “stop on a dime”, both meaning an action done instantly.  Drop and stop are four letter words that rhyme, adding to the befuddlement.  This beauty was heard at a court hearing.  Kudos to Sam Edelmann for sending this one into Malaphor central!