Does anybody know what the phrase " PLEASING STREAM OF THE OLD RANCID" means ?

Hotel proprietress Maggie Smith said "I was giving the hired help a pleasing stream of the old rancid" it to Peter Ustinov playing Hercules Poirot in the film adaptation of the 1941 Agatha Christie novel Evil Under The Sun, gave the example of the chef's curry vindaloo methegeba being so hot it burned the roof of the mouth, and more or less corresponds to later colloquiallisms such as 'Giving them an earful' or 'Telling them to get their act together'