Note: For the game called AFGNCAAP, see AFGNCAAP - IF Agent! Todays Adventure: Holy Goat! (Marius Müller; 2007).
AFGNCAAP is an abbreviation that stands for Ageless, Faceless, Gender Neutral, Culturally Ambiguous Adventure Person. The term comes from Zork Grand Inquisitor, where one of the NPCs (Dalboz of Gurth) gives the PC this name. It is essentially a joking reference to the convention of Infocom games to encourage players to conflate the story's protagonist with themselves; a practice which necessitates the protagonist having the most generic identity possible.
AFGNCAAP is pronounced like "afghan-cap" (if you're British) or "afghan-cop" (if you're American).
See also: the Everyman trope.