Literally stands for "Raped Faggot". Used mainly in forums and in mmorpg's to bypass the language filters.
1. Prevalant mostly in the PvP gaming community to describe a player, or a group of players, that got beaten very badly.
2. Used to let someone know that they have been trolled
Player 1: "Omg the two of us just wasted all 6 of those dudes, they need to l2p
Player 2: "LOL yeah RPD FGT."
Poster 1: "Hey everyone look at my build!" (posts build)
Poster 2: "Noob why are you stacking ballistic skill on your knight?"
Poster 3: "rpd fgt"