Out Of Character Meaning

(idiomatic, drama, role-playing games) Not acting; not "on"; behaving within one's natural personality rather than that of a character, or taking actions entirely outside the fictional context.

Example:   The burst of anger was out of character for the normally placid boy.
2012 April 29, Nathan Rabin, “TV: Review: THE SIMPSONS (CLASSIC): “Treehouse of Horror III” (season 4, episode 5; originally aired 10/29/1992)”[1]:
  In “Treehouse Of Horror” episodes, the rules aren’t just different—they don’t even exist. If writers want Homer to kill Flanders or for a segment to end with a marriage between a woman and a giant ape, they can do so without worrying about continuity or consistency or fans griping that the gang is behaving out of character.
  I was out of character for most of the first act because those people in the third row wouldn't stop chatting.
  After watching him perform so energetically, it is a bit of a trip to hang out with him when he's out of character. In real life, he's really mellow.
  Susan asked the GM, out of character, whether she was able to sense magic in the room.