The phrase "act out of character" is correct and usable in written English.
It can be used to describe someone behaving in a way that is inconsistent with their usual personality or behavior.
Example: "Seeing him lose his temper like that was surprising; he usually remains calm, so it was clear he was acting out of character."
Alternatives: "behave unexpectedly" or "act uncharacteristically".
"There's a lot of acting and spinning involved, and it's easy to act out of character – one of the things that always interested me is the idea of being thrust into an unelected friendship group, people you didn't choose to be friends with, and the effects that can have on your personality.
In the delirium of summer, we have the brief chance, perhaps, to act out of character.
Turbulent times can make the best of us act out of character, Cheryl Cole (@cherylcole).
And yet there must have been some reason: Nick "knew in his heart that people didn't act out of character.
And as the personality psychologist Brian Little says, we all need to act out of character occasionally, for the sake of work or people we love.
Opposition politicians see Temer as a cautious figure who is being forced to act out of character due to the severity of the problem facing Brazil.
Given this history, many people who were close to him believe that his death was not an act of will, but, like other sleepwalking episodes, a bizarre out-of-character act that ended tragically.
In an unexpected reaction to Mike Huckabee's statement that Democrats don't trust libidinous women to control themselves, women across the country have been throwing themselves into wanton and often out-of-character sex acts.
"The movie is banned because for us Muslims, we believe in Prophet Noah (Nabi Nuh) and, according to Islamic teachings, it is prohibited to act out any characters of a prophet," chief censor Abdul Hamid told the Sun Daily.
A lot of his words were brilliant, but they were poetry – not the sort of language you could act out a character with.
My daughter's young protégé is a great student, but, probably under stress, acted out of character.
