"Fancy pants" is a casual, colloquial term used to describe someone who is excessively showy or pretentious. Synonyms for this phrase include "snob," "show-off," "haughty," "taut," "arrogant," "uppity," and "pretentious." These phrases seek to describe someone who places a high value on their appearance, social standing, or wealth - someone who might look down on those they believe to be beneath them. Other words that might be used in place of "fancy pants" could include "conceited," "egotistical," or "vain," as these terms connote a sense of self-importance or ego-driven behavior that is often associated with the idea of being "fancy pants".