the upper crust the aristocracy and upper classes. informal

☞ In Anne Elizabeth Baker's Glossary of Northamptonshire Words and Phrases (1854) 'Mrs Upper Crust' is explained as the nickname for 'any female who assumes unauthorized superiority'. The term was also current in informal American speech in the mid 19th century. The French word gratin has a similar pair of literal and metaphorical senses, being literally 'a crust of crumbs and cheese on top of a cooked dish' and metaphorically 'the highest class of society'.