Ragnarok Online; a MMORPG released by Koran based Gravity corp, quite often played on by private servers like many games that have gone p2p (pay to play). Many players that play iROSE have at one point played RO.
Short for "Rot Off." A rot off is a member of the female persuasion who, as a result of engaging in sexual intercourse with multiple partners (males, females, animals etc.), is a host to a number of venereal diseases. The R.O. will then procede to spread the diseases, resulting in her partner's genitals rotting off.
R.O.'s include but are not limited to: