He finally showed his true colors during the argument.
show one's true colors
idiomTo reveal how one really is, as opposed to how one has been portrayed or after having been deceptively and deliberately misleading.
Origin
disputed originNautical origin. The word colors (or colours) 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 true colours.
She seemed very kind at first, but she showed her true colors when things went wrong at work.
The politician maintained a facade of integrity for years, but the scandal forced him to show his true colors to the public.
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abound in one's own sense
To follow one’s own inclinations and opinions.
- 02
ace up one's sleeve
A surprise advantage of which others are not aware.
- 03
act one's age
To behave in a manner appropriate to one's age.
- 04
act one's age, not one's shoe size
Synonym of act one's age (“to behave in a mature manner; to avoid being childish”).
- 05
afraid of one's own shadow
Exceptionally timid.
- 06
air one's dirty laundry in public
To reveal one's sordid secrets to the public.
- 07
air one's dirty linen in public
Synonym of air one's dirty laundry in public.
- 08
albatross around one's neck
A characteristic, possession, associate, or previous deed that hinders one's ability to succeed.