Rocket Propelled Grenade, you roleplaying geeks.

Short for "Role-Playing Game"; a game in which the player takes on the persona of a fictional character and has adventures with other characters in a world created by the Game-master, a sort of referee. Can be played with other people ("Face-to-Face" or "table-top"; also called "Pen-and-Paper"), or over the Internet ("Play-by-E-mail" or "Play-by-Post" games; this category also includes games played on IRC or via a chat site)

Not to be confused with computer RPGs, which are a different kettle of fish altogether.

(1) Rocket Propelled Grenade. Used in combat situations.
(2) Role Playing Game (tabletop). Game in which the player takes on another personality to have fun.
(3) Role Playing Game (video game, turn based). A game that is frowned upon by fans of FPS for it's strategical approach. More easily described as a "Playable Anime".
(4) Role Playing Game (video game, active battle). Fast paced, can appeal to even FPS fans. I have personally proved this in 5 cases.

RPG stands for Ruchnoy Protivotankovy Granatomyot

Translated, that means handheld anti-tank grenade.

The RPG does fire a rocket propelled grenade, but that isn't what the acronym stands for.

Rocket Propelled Grenade. It can effectively destroy any light to medium (maybe) armored vehicles. It is used by many countries that bought the blue prints from the soviets during the cold war, same story as the AK47.

Short for Roleplaying Game. Table top or otherwise that allows one or more people to assume a fictious alter-personality, or personalities, and live a story while having the ability to make choices to directly alter the experience and/or the outcome.

Not to be confused with most "Japanese console rpg's" or as the kiddies refer to as "RPG-Lite" games such as Final Fantasy, Wild Arms, Dragon Warrior, Secret of Mana, etc. Such games play on the sensationalizing of the term "RPG" to make a buck in the market and in all actuality offer no authentic "Role Playing" experience.
The most they can be described as is simply "interactive anime" or "pop up books with batles".

RPG does not actually stand for Rocket Propelled Grenade, the abbreviation actually comes from the Russian phrase for "hand-held anti-tank grenade-launcher": Ruchnoi Protivotankovye Granatamyot.