put on the dog

to put on (the) dog also to put on the Ritz {US}(make a flashy display; behave or dress in an ostentatious or showy manner; try to seem richer or more important than you really are; show off) — рисоваться; пускать пыль в глаза; пытаться произвести впечатление (рисуясь) || важничать; держаться высокомерно; задирать нос; пыжиться, хорохориться, становиться в позу

Example 1: My parents really put on the dog in front of their guests. — Мои родители из кожи вон лезут, чтобы произвести впечатление на гостей.

Example 2: “The annual ball gave everyone a chance to dress up and put on the dog.” (The New Dictionary of Cultural Literacy)

Example 3: She really put on the Ritz for his parents last weekend.

also
[put on airs]
[high horse]
[понты]
to cut a swell
[из кожи вон лезть]

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It has been suggested that it developed out of the rise in popularity of ladies’ lap dogs in the period after the American Civil War. Such animals were presumably pampered and beribboned, and this might have suggested that to put on the dog was to show off. This has the ring of a story made up after the event, but it’s the only explanation we’ve come across. (worldwidewords)