显山露水 (xiǎn shān lòu shuǐ) is a four-character idiom that literally means 'to reveal mountains and expose water'. Figuratively, it describes someone revealing or showing off their hidden talents, abilities, or accomplishments. It often carries a critical tone — implying the person is being too showy or eager to display themselves, especially after keeping a low profile. Use it to comment on someone's competitive or boastful behavior.