OOC

From the White Wolf Wiki, the most complete White Wolf reference

OOC is an abbreviation for "out of character". Originating from online RPGs such as MU* (and, later, MMORPGs like EverQuest), some pen-and-paper troupes have taken to using it in game to denote when they are speaking as themselves and not as their character. It can be said in its abbreviated form (O-O-C) or pronounced as "ook".

See also: IC