The phrase "most la de da" refers to something that is considered to be pretentious or overly refined. There are many synonyms that can be used to describe something that falls into this category. Some examples include: affected, aristocratic, cultured, fancy, highbrow, hoity-toity, ostentatious, posh, refined, snobby, stylish, and upscale. These words are often used to describe people who are perceived as being snobbish or pretentious, or to describe things such as clothing, furniture or artwork that are considered to be too expensive or ostentatious. Using these words can help to convey a sense of disdain or disapproval for something that is deemed to be excessively "la de da".