show one's true colors

Etymology
Nautical origin. The word (or ) refers to the flag or ensign which every ship is obliged to fly at sea. It was once a common deception of pirates to “sail under false colours” and fly a friendly flag in order to get within close range of potential targets (other ships) without exciting suspicion. Only when the pirate ship reached close quarters would it unfurl its.

Verb

 * 1)  To reveal how one really is, as opposed to how one has been portrayed or after having been deceptively and deliberately misleading.

Translations

 * Chinese:
 * Mandarin: 露出真面目
 * Czech: vybarvit, odhalit své ledví
 * Danish:
 * Finnish: näyttää todellinen karvansa
 * French: se montrer sous son vrai jour, montrer son vrai visage
 * German:, sein wahres Gesicht zeigen
 * Hungarian: kimutatja a foga fehérjét, megmutatja valódi arcát,
 * Italian: mostrare il proprio vero volto
 * Malay: tunjuk belang
 * Norwegian: vise sin sanne natur, stikke hestehoven fram
 * Polish: pokazywać prawdziwą twarz, pokazać prawdziwą twarz
 * Portuguese: mostrar sua verdadeira cara
 * Russian: показа́ть истинное лицо́
 * Spanish: mostrar su verdadera cara, mostrar sus verdaderas cartas, mostrarse tal cual es, vérsele las costuras
 * Swedish: visa sitt rätta ansikte, visa sitt rätta jag, visa sin sanna natur,
 * Thai: