No, anyone who hasn't had contact with DnD (Dungeons and Dragons) wouldn't know what the heck I am talking about.
PHB - Player's Handbook: The guide that every DnD player shouldn't be without, tells you how to create a character and level up, along with equipment and spell lists and anything else you need to play.
MM - Monster Manual: A listing of creatures (mostly evil 'Monsters') that may be encountered in the DnD universe, along with stats for each. A vital reference for DMs (Dungeon Masters).
DMG - Dungeon Master's Guide: The guide that every DnD DM shouldn't be without, tells you how to set up an adventure, how to create NPCs (Non-Player Characters, anyone not controlled by a player), how to run an adventure, and generally be the referee for the players.
If you are still curious after all that, try the wikipedia page on DnD, or, better yet, look up a group that plays in your area and give it a try. (just ask around any geek friends you have, someone knows someone who plays, trust me)
Oh, and OMFG is general AOL-speak for Oh My Fucking God, which I put in to be humorous both because of the fact that we are talking about God, and because of all the other Acronyms in the post. (Surgeon General's Warning - The use of AOL-speak in any situation where it is not used for humor may be hazardous to your intelligence. Please type responsibly.)