Rappan Athuk

From 1d4chan

Rappan Athuk is Necromancer Games' super-dungeon /slash/ Adventure Path, for d20 / 3e Dungeons & Dragons.

Infamous for a big mobile pile of poo that the party cannot kill, affectionately termed "Dungie".

It sold like hotcakes, the module I mean not the poo. So it got upgraded.