Greg asked for it:
Crapout. A dead-end passage, esp. one filled with dirkle.
Dirkle. Calcified feces of unknown origin found in abandoned lairs; e.g. "Bah! What kind of hoard is this? 'Tis nothing but a handful of coppers and dirkle!"
Earwasher. A narrow, low-ceiling water-filled passage which must be crawled through while dragging one ear in the water and one on the ceiling in order to pass; e.g. "When you hit the big pool, head to the left and take the earwasher through to the treasure room!"
Frump. To explore or enter previously unexplored underground passages, e.g. "We somehow frumped our way into a flail snail mating cavern--it was horrible!"
Frumping Canary (also Frumping Thrush or Frumping Fool). The person taking point and leading the way through a previously unexplored underground complex.
Goosh. Water-softened rations warmed over a lantern or torch and thus sooty and foul-tasting; e.g. "Gimmie some of that there goosh, Artrec--don't hogs it all for yourself!"
Knobby Goblin. A quickly improvised ladder using rope and any convenient rungs lashed to the rope by any at-hand means. E.g.: "It was too far to jump down, so we made a knobby goblin out of some rope and our spears and quickly made the descent."
Snuffler. An extremely narrow passage that can only be traversed naked and by not inhaling.
Uulate, most likely derived from the Gnomish ewlatte, the first breath of a new-born gnome. The low, incessant hum pulsing from the earth in the deepest, darkest parts of the underdark when one stops, stands still, and breathes. No one has discovered its true source, but rumors abound that it is the breath of an Elder God or deity of Goetic Magic that has been trapped between planes.
Winsler. A vertical shaft in a mine or cavern that appears to lead to the surface but merely bridges two levels. Example: "There we were six levels beneath Crackton's Tower and I saw a light up the shaft right above us. It had to have been the way we got down there in the first place, so I hit myself with a Fly spell and took off up the shaft only to slam my head into the top of that damn winsler!"
Winkie. A fraying rope, esp. one fraying while lifting or lowering a heavy load; e.g. "Hurry up and drag Balton up here--that rope is a winkie and we don't want him making any noise if it lets loose!"