The idiom “put on the dog” means to act or dress in an extravagant or ostentatious manner, often in an attempt to impress others or to show off wealth and sophistication. It can also refer to behaving in a way that is overly flashy or pretentious.
For example, if someone goes to great lengths to display luxury items or to host a lavish party to impress their guests, you might say they are “putting on the dog.” The phrase suggests a level of showiness that may not reflect a person’s true lifestyle or values, indicating an emphasis on appearance over substance.
The idiom has its roots in the early 20th century and is often associated with social status and the desire to create a certain image in public.